Building Wonders

See how three magnificent ancient structures were engineered in this three-part series. Airing February 11, 18, and 25, 2015 on PBS. Airing February 11, 18, and 25, 2015 on PBS.

Program Description

In "Building Wonders", NOVA presents three groundbreaking shows that investigate engineering mysteries of the ancient world with the help of dramatic hands-on experiments. In "Colosseum: Roman Death Trap," NOVA explores how the ancient Romans built their vast stadium so they could reenact naval battles and stage spectacles involving hundreds of gladiators and wild animals. In the middle of Jordan's parched desert, a NOVA team investigates the "Petra: Lost City of Stone," once a thriving metropolis of temples, markets, and spectacular tombs carved into cliffs. How did Petra's architects supply running water to this bone-dry canyon for bathhouses, fountains and pools? In "Hagia Sophia: Istanbul's Ancient Mystery," modern architects use medieval tools to figure out why Turkey's massive 1,500 year-old cathedral dome has survived countless quakes in one of the world's most violent seismic zones.

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Colosseum: Roman Death Trap

1500 years ago, how did the Romans engineer bloody spectacles and reenact sea battles? Airing February 11, 2015 at 9 pm on PBS Aired February 11, 2015 on PBS

Program Description

One of the ancient world's most iconic buildings, the Colosseum is a monument to Roman imperial power and cruelty. Its graceful lines and harmonious proportions concealed a highly efficient design and advanced construction methods that made hundreds of arches out of 100,000 tons of stone. In its elliptical arena, tens of thousands of gladiators, slaves, prisoners, and wild animals met their deaths. Ancient texts report lions and elephants emerging from beneath the floor, as if by magic, to ravage gladiators and people condemned to death. Then, just as quickly, the Colosseum could be flooded with so much water that ships could engage in sea battles to the delight of the crowd. Now, archaeologists and engineers are teaming up to recreate a 25-foot lifting machine and trap door system capable of releasing a wolf into the Colosseum's arena for the first time in 1,500 years. Do they have what it takes to replicate the innovation and ingenuity of the Romans?

Transcript

Colosseum: Roman Death Trap

PBS Airdate: February 11, 2015

NARRATOR: The Colosseum: the Roman Empire summed up in stone. Never has such a civilized culture poured so much of its wealth into engineering spectacles of death for the entertainment of its people.

KATHERINE WELCH (New York University): In the morning, you had wild beast shows; around the lunchtime, crucifixions; in the afternoon, the piece de la resistance: two men, fighting to the death.

NARRATOR: Ancient Roman accounts document the Colosseum's repertoire in chilling detail. They depict an orgy of outrageous spectacles: costumed gladiators cast in battles to the death; exotic animals unleashed on unsuspecting victims; even sea battles, with thousands of people killed.

Were the Romans as bloodthirsty in their theatrics as ancient authors report?

To investigate, a subterranean archeologist explores tunnels beneath the Colosseum to discover how it could be flooded for naval battles. A forensic scientist gives voice to gladiators whose battle-bruised bones bear witness to their own deaths.

FABIAN KANZ (Medical University of Vienna): We had in our hands, for the first time, remains of real gladiators.

NARRATOR: And an architect pieces together clues of an elaborate system of ancient special effects machines. Then, with a team of engineers and builders, they reconstruct it, and for the first time in 1,500 years release an animal into the Colosseum.

Now, can scientists and scholars unlock the secrets of how and why the Romans engineered such bloody spectacles? Right now, on NOVA, The Colosseum: Roman Deathtrap.

If one building best symbolizes the gore, glory and genius of the Romans, it is the Colosseum. It is a spectacle of design and engineering, the biggest building they ever constructed. It spans nearly 2,000 feet around, soars over 160 feet high, and soon after it opened, in the year 80, it was decorated in gleaming bronze shields and 16-foot statues of gods and heroes.

To this day, the Colosseum stands as a powerful landmark on the skyline of Rome.

MARK WILSON JONES (University of Bath): When the Colosseum was built, it had enormous effect, because of its size, status and presence in Rome.

NARRATOR: The echo of its 50,000 spectators cheering bloody theatrics continues to haunt imaginations: gladiators fighting to the death, mass crucifixions, elaborate animal hunts. Over four centuries, the Colosseum was witness to an estimated million human deaths, and with up to 11,000 animals killed in a season, some species, like the Balkan lion and a North African elephant, were driven to extinction.

Yet the Colosseum was much more than a spectacular slaughterhouse. It was a carefullyengineered entertainment complex, designed to reinforce Roman world order.

KATHERINE WELCH: Watching fighting on a regular basis for entertainment gave the Romans a sense of who they were and infused them with a kind of military ethos that was instrumental in creating and maintaining the empire.

NARRATOR: Ancient Roman authors, such as Martial in his Book of Spectacles, describe how that world order played out on the arena's stage. They cast the Emperor as master illusionist.

On his command, a menagerie of ostriches, crocodiles, rhinos, bears and tigers magically appear to be dispatched by hunters; a condemned criminal is dressed in wings and catapulted across the arena to play out a Greek myth; and fantastical sea battles take place, where thousands of prisoners of war are either slaughtered or drowned.

Can these astonishing accounts of elaborate executions be true? Or has the boundary between history and myth been blurred over time?

Most recently, the Colosseum was brought back to life in the film Gladiator, where tigers spring from out of nowhere to maul Russell Crowe. But that's Hollywood effects; the Romans were doing it for real.

Parts of the movie Gladiator are based on events portrayed in ancient texts and mosaics. They depict gladiators locked in combat and wild beasts mauling people. But none of these accounts describe how the Romans made these animals magically appear.

Some scholars suspect the secret may be hidden in its basement. The “hypogeum,” the Greek word for “underground” is a maze of corridors and collapsed walls.

Architect Heinz Beste thinks that here, hidden from the spectators above, is where the Romans engineered their murderous magic.

HEINZ BESTE (German Archaeological Institute in Rome): We have to imagine this being covered by the wooden arena floor above. It was dark down here, lit only by torches and small lamps.

NARRATOR: Today, the arena floor has been partially rebuilt for tourists. The original was made of wood and covered in sand, to absorb blood. The floor and all its wooden supports are long gone, but etched into the walls of the hypogeum Beste finds deep cuts and grooves.

To decipher these fossil-like remains, he drew every stone on every wall. After more than two years, he began to make sense of the mysterious markings.

HEINZ BESTE: Through these drawings, it was possible to connect these clues and turn the whole puzzle into a system that can be explained.

NARRATOR: Here, he finds impressions made by wooden beams, and, evenly spaced along the floor, are a series of round holes in concrete.

HEINZ BESTE: Here is another piece of the puzzle. This is a base for a capstan.

NARRATOR: A capstan is a large round pole that could be turned by workers to lift something.

HEINZ BESTE: Ah, interesting. Up here, we see an indentation for a ramp.

NARRATOR: Another mark reveals where a ramp might have led to the arena.

In Beste's mind, the pieces come together: support framing from the floor of the hypogeum to the floor of the arena, halfway up, a horizontal beam for workers to stand on, a capstan with poles for workers to turn, a channel where a cage could fit, and finally, a trapdoor that could lower to become a ramp leading to the arena floor. Together, they form what could be a device to lift and release animals.

HEINZ BESTE: I believe, given the evidence, there must have been an ancient lift system here.

NARRATOR: Throughout the hypogeum, Beste finds evidence of ancient backstage machinery, a total of 28 lifts. Has Heinz Beste discovered the secret to how the Romans made wild animals magically appear in the arena?

To find out, he wants to construct a lift and trapdoor system, install it right here in the Colosseum and raise an animal into the most famous amphitheater on Earth.

But why did the Romans build the Colosseum to stage these bloody spectacles? Part of the answer is hiding in plain sight.

For years, a cast-aside stone was used as a place for visitors to rest, its importance completely unnoticed. In the 1800s, an inscription was discovered on its surface. It ended up here, in the Colosseum museum, where it became, once again, largely unnoticed. But hidden beneath these fifth-century letters may be another, much earlier inscription.

Rosella Rea is Director of the Colosseum and one of the leading experts on the building. Mixed within the engraved letters, she sees a series of strange holes.

ROSELLA REA (Director of the Colosseum): You can see with the naked eye that the holes are arranged in a regular pattern. By studying their layout, it was found that the holes form a series of letters.

NARRATOR: The holes are where bronze letters had once been fastened to the stone.

ROSELLA REA: This was the hole for the first letter, the letter "I" for "imperator.”

NARRATOR: Or “emperor.” Connecting all the dots reveals the original inscription. “The Emperor Vespasian ordered this new amphitheater to be constructed from the booty…”

Vespasian Flavius becomes emperor in the year 69. The following year he orders construction on the Colosseum to begin.

The stone is the plaque from its dedication, and the letters spell out how the Colosseum was paid for, with booty. But booty from where?

Vespasian's son left a clue on the nearby Arch of Titus. On it, Katherine Welch finds depictions of Romans sacking the temple in Jerusalem.

KATHERINE WELCH: One of the panels depicts the menorah, the Torah and the sacred table, carried by elite young Roman men. This is quintessential war booty, the things that meant the most to the people from whom they were seized.

NARRATOR: Following his son's conquest of Judea in the year 70, Vespasian is rich with gold and slaves. He can build anything he wants. So why the Colosseum?

Vespasian needs a building that makes a bold statement that he, Vespasian Flavius, is nothing like the emperor before him, the infamous Nero.

Emperor Nero's rule is marked by extravagance, and much of Rome burning. He confiscates land and builds a pleasure palace with gardens and a manmade lake. Nero is driven from the throne, commits suicide, and Rome is engulfed in civil war.

KATHERINE WELCH: After a ghastly year of civil war and the suicide of Nero, Vespasian did everything in his living power to ingratiate himself with the Senate and consolidate his personal power.

NARRATOR: After fighting his way to the throne, Vespasian casts himself as the anti-Nero. He buries Nero's palace, fills in his lake and on top builds the opposite of a pleasure garden, a public building for blood sports.

KATHERINE WELCH: In building the largest, most expensive building in Rome, a building for popular entertainment, it celebrated military power and put it into a frightening, exciting, chastening context.

NARRATOR: The Colosseum is the perfect symbol for how Vespasian and Rome came to power. And to enhance the blood sports, Vespasian builds in some deadly surprises, releasing wild animals into the arena.

But reconstructing the lift that could have done this is an audacious plan. If Heinz Beste is to succeed, he'll need to find an ally on the inside.

Umberto Baruffaldi is an engineer, inventor and GoPro enthusiast. He, too, is captivated by how the Romans released wild animals into the arena. Umberto also happens to be director of Health and Safety for the Colosseum.

Beste shares his drawings with Umberto.

UMBERTO BARUFFALDI (Designer/Engineer): The drawing is beautiful, but how are we going to make it work?

NARRATOR: Beste's drawings provide a skeleton of the system, but it's not clear how the lift actually works.

Umberto brings in structural engineer Giovanni Squillacioti and material engineer Flavia Campanelli.

FLAVIA CAMPANELLI (Structural Engineer): We have to create a system of pulleys and counterweights that works perfectly and synchronizes.

NARRATOR: Giovanni translates Beste's two-dimensional drawing into a three-dimensional computer model.

GIOVANNI SQUILLACIOTI (Architect/Designer): I defined every mechanism that Flavia has indicated.

NARRATOR: The trapdoor is one of the big challenges. On one hand, it has to open to release the animal into the arena,…

UMBERTO BARUFFALDI: So when it opens, the animal jumps up and goes out in the arena.

NARRATOR: …but when it's closed, it has to support the weight of gladiators, charioteers and heavy animals trampling on it, above.

Giovanni puts the pieces together and connects them, in his computer model, with pulleys, ropes and hinges.

UMBERTO BARUFFALDI: Perfecto.

NARRATOR: Then, based on Giovanni's 3-D wizardry, Heinz and Umberto build a scale model.

HEINZ BESTE: Can we add a hoist here?

UMBERTO BARUFFALDI: A crank handle?

NARRATOR: At the heart of the system is the capstan, a large central pole. As this is turned, it wraps a rope around it.

The animal is placed in this cage. It's connected to the capstan through a series of pulleys, so as the capstan is turned, the cage rises. Two large hinged arms support the trapdoor when it's closed, and then swing down to open it. As the cage rises, the door automatically opens, releasing the animal onto the ramp.

UMBERTO BARUFFALDI: The model is essential to experimental work of any kind; because it is the model that allows you to understand all the mechanics.

NARRATOR: And building the lift and trapdoor system will provide a window onto a uniquely Roman pastime, in a uniquely Roman building, the amphitheater.

Mark Wilson Jones is an architect with an expertise in Greek and Roman buildings. He's here in Arles, in southern France, at an amphitheater constructed about 20 years after the Colosseum.

MARK WILSON JONES: In general, the Romans took their building forms from the Greeks, but this is not the case for the amphitheater. The amphitheater was a definite Roman invention. And they created it for the special circumstances of gladiatorial fights.

NARRATOR: “Amphi” means “double” in Greek, and “amphitheater” translates as “double” theater.

But if a Greek theater were just doubled it would be round. The Roman amphitheater is actually a stretched circle, or an oval. Wilson Jones believes the Roman's innovation of the oval shape may be a direct result of the building's function, a place for gladiator combat.

MARK WILSON JONES: Most buildings are rectangular, and that's a bad thing, because you can get action stuck in the corner.

NARRATOR: If a gladiator gets stuck in a corner, he gets killed quickly. The oval shape helps prolong the action for maximum entertainment value.

MARK WILSON JONES: So this shape has a dynamic quality, no corners. Everything's smooth, so the action can move around. And I think that really suits the action, and it helps it, helps it maintain its, sort of, excitement.

NARRATOR: An amphitheater for gladiator combat is uniquely Roman in form and function, exactly the symbol Emperor Vespasian needs to project his power and inspire Roman pride.

MARK WILSON JONES: There's this strong connection between the unique shape of the amphitheater and the gladiatorial performances, the link with the military, the conquest of empire. The great crowds of 50,000 that came together in the Colosseum, were celebrating all of that. It's really a sort of great day out to feel a Roman citizen and feel at the center of the world.

UMBERTO BARUFFALDI: It's the perfect day. Look what a beautiful day it is.

NARRATOR: In a forest northeast of Rome, Umberto is in search of the perfect tree for making the lift.

TULIO CLEMENTINI (Carpenter): It should be about four meters high.

NARRATOR: The tree will be used for one of the key parts of the lift, the capstan.

UMBERTO BARUFFALDI: Here, this is our tree.

NARRATOR: To fell the tree, the team uses the same tools as the ancient Romans, the ax, the two-man saw and a wedge.

Carmelo Malacrino, an expert on ancient Roman building, knows what tools to use from images on the Trajan Column, erected just 30 years after the opening of the Colosseum.

CARMELO G. MALACRINO (University of Reggio Calabria): This column shows a fantastic series of tree cutting. It depicts the deforestation process for constructing new roads and the creation of campsites, as part of a military campaign.

NARRATOR: After an hour of chopping and sawing, the tree comes crashing down.

Now the tree begins its transformation into the capstan. But Umberto leaves a little bark as a reminder of where it came from.

The team uses their scale model as a guide for building the lift.

UMBERTO BARUFFALDI: The move from that model to the real thing was a little traumatic. Working in a dimension four-times bigger really amplifies the problems.

NARRATOR: The cage itself will weigh over 800 pounds. It needs to be strong to keep wild animals inside.

TULIO CLEMENTINI: We have to pay attention to the sturdiness of the cage, since it's supposed to hold lions and tigers.

NARRATOR: Seeing the lift at full-scale, Umberto starts to have some concerns.

UMBERTO BARUFFALDI: The most difficult part will be getting the lift in without touching the Colosseum, because if we damage the Colosseum, I'll be chased out of the Colosseum.

NARRATOR: Today, the Colosseum is a majestic ruin. Over the centuries, everything of value was stripped from its walls. But coins minted for its opening and carvings on tombs show how the Colosseum was likely decorated.

In its arches, stood 160 bronze statues, 16 feet tall, representing gods and heroes the Romans borrow from the Greek pantheon. At its top layer were gleaming bronze disks symbolizing captured shields. Finally, framing the arches, were columns of various architectural orders: Greek capitals on the upper three layers, but on the street level are Roman capitals.

KATHERINE WELCH: Vespasian is giving the people, the “plebs Romana,” exactly what they want, Greek orders, Greek statues, but all with a Roman twist and pressed into the service of the conquering Roman state.

NARRATOR: The Colosseum's decorations amplify the message of the building's monumental scale: we Romans love Greek art and culture, but we have surpassed them; Rome is the new superpower.

As a final touch, there was a bronze chariot above the entry arch on the north side, where the Emperor could make his grand entrance, but Vespasian will never walk beneath it. He dies just months before the Colosseum is completed. He does leave a lasting legacy though: the largest building in Rome and an imperial dynasty.

For the first time in Roman history, an Emperor is directly succeeded by his natural son. In the year 80, Titus holds the inaugural games in honor of his father.

Roman author Martial in his Liber Spectaculorum, the Book of Spectacles, describes the inaugural games: a hundred days of crucifixions; wild beast shows; gladiator combat; and, for the first time, the acting out of Greek myths with elaborate scenery and actual deaths.

KATHERINE WELCH: What happened with the inauguration of the Colosseum is that Greek mythological executions entered the arena repertoire. Except, in the theater, they were bloodless, they were just actors; in the amphitheater, they were condemned criminals who were forced to dress up as Greek mythological characters and killed in the Colosseum.

NARRATOR: The Romans would reenact well-known Greek myths, such as Icarus flying too close to the sun and falling to Earth. But in the Colosseum, there was a gruesome twist. The criminal playing Icarus would be catapulted across the arena to his death.

KATHERINE WELCH: This is not a myth. It's real!

NARRATOR: Martial goes on to describe a mass execution, so cruelly choreographed it surpasses even Roman standards: naumachiae, mock sea battles where ships are sunk with hundreds of prisoners on board.

What astonishes Martial is not the mass murder by drowning, but rather how it was pulled off. How could the Colosseum be flooded for sea battles in the morning, then drained quickly enough for gladiator combat in the afternoon?

The Romans were masters of moving water. A network of 11 aqueducts carried clean water to Rome from mountain springs, some over 50 miles away. The aqueducts provide the means to get water into Colosseum, and new discoveries are revealing a system to get water out of the Colosseum.

Adriano Morabito, director of Subterranean Rome, has spent 10 years mapping the city's underground water system. One day, while surveying for a new metro line, he took an unexpected turn.

ADRIANO MORABITO (Roma Sotterranea): We were mapping all the sewage system, and, suddenly, we went into an older drainage system, and we saw light at the end.

NARRATOR: To his great surprise, the light at the end of the tunnel was the Colosseum. Morabito had stumbled into an ancient drain or “collector.”

ADRIANO MORABITO: This is the only collector still working today. In ancient times, we had all four collectors getting rid of the water out of the monument.

NARRATOR: Beneath the arena, Morabito finds evidence of four drains that emptied water from the Colosseum. And climbing to the top of the hypogeum, Morabito finds 40 channels that may have fed water in.

ADRIANO MORABITO: Some archeologists speculate that this could have been used to flood the arena.

NARRATOR: Morabito believes the 40 input channels and four drains provide the plumbing to stage naval battles.

To put his theory to the test, he investigates how much water the Romans would need to flood the arena.

He finds four passageways leading into the hypogeum, wide enough to launch flat-bottomed boats into the arena.

ADRIANO MORABITO: When the arena was flooded, the water was coming in here, and then the boats were starting floating up to this level, because otherwise the water would have gone into other rooms.

NARRATOR: Morabito reasons the water could have been no higher than about five feet or it would spill over into other areas of the Colosseum.

Multiplying that depth by the area of the arena, he calculates, with the floor removed, it can hold a million and a quarter gallons of water, equal to about two Olympic swimming pools.

But can the drains empty that much water fast enough to stage sea battles and gladiator fights all in one day, as author Martial describes?

One night, a thunderstorm puts Morabito's theory and the surviving drain to the test. The storm dumps 800,000 gallons of water into the Colosseum, filling the hypogeum half way. That rainwater, with just one drain, empties in under two hours.

Morabito calculates that, with all four drains working, the Colosseum could be emptied in less than an hour.

ADRIANO MORABITO: It was, therefore, technically possible for the emperor's engineers to flood the arena for it's opening games.

NARRATOR: Morabito believes the Romans had the plumbing and enough water to stage mock sea battles in the Colosseum, just as ancient texts claim. But could they really lift animals into the arena?

After months of constructing the lift and trapdoor system in the workshop outside of Rome, today, the pieces finally arrive: the 440-pound trapdoor, the 2,000-pound frame and nearly 1,000-pound cage and the capstan, weighing in at 500 pounds.

Originally, the pieces were built right into the walls of the hypogeum. But today those fragile walls are a part of a protected World Heritage Site that can't be altered. So their idea is to pre-assemble the lift outside the Colosseum and then drop it into place as one self-contained unit.

GIOVANNI SQUILLACIOTI: Assembling the lift is a tricky process, almost as tricky as the design. It's big and bulky. And then lowering into the Colosseum is the most difficult part.

NARRATOR: Umberto has hired a 200-foot crane for this delicate operation. Giovanni Cirillo is behind the controls.

GIOVANNI CIRILLO (Crane Operator): The only issue today is the wind. And the later it gets in the afternoon, the windier it gets. That might shake the structure and make my job less exact.

NARRATOR: After hours of assembling, the team is finally ready to raise the lift. The crane hauls the machine to a standing position and then stops. There's a problem.

The crane has a built-in scale, and Cirillo discovers the lift is too heavy.

GIOVANNI CIRILLO: The load is 600 kilos overweight. Over this distance, that's a problem.

NARRATOR: The crane has the power to raise the lift, but when its arm extends out over the Colosseum, too much weight could cause the crane to tip over.

UMBERTO BARUFFALDI: We don't know if we can get the lift inside. The main issue is the crane might topple over.

NARRATOR: The team does some quick math to try to save the project.

GIOVANNI SQUILLACIOTI: According to our calculations, the cage weighs around 450 kilos, so that, once we take that away, the load will be lighter for the crane.

NARRATOR: They remove the cage, but they're still 150 kilos, or about 300 pounds over.

Umberto confers with Cirillo and takes a calculated risk. He green-lights the raising of the lift.

The crane hauls the lift up nearly 200 feet and over the walls of the Colosseum. Umberto holds his breath as the crane's arm stretches out over the hypogeum. This shifts the crane's center of gravity. If the lift is still too heavy, the crane could topple over, crashing into the Colosseum and smashing the lift into the hypogeum.

To make it even more challenging, Cirillo has to maneuver the lift without even being able to see it, guided only by radio contact.

Rosella Rea, director of the Colosseum, and perhaps the person with the most riding on the success or failure of the lift project, arrives at the critical moment, as the team steers the lift between the narrow, fragile walls of the hypogeum, with almost no wiggle room.

To everyone's immense relief, the lift slides in perfectly.

After flying the three-ton lift into place, the half-ton cage is a breeze.

HEINZ BESTE: Well, when you look at it as a drawing, when you imagine it in your mind's eye, or when you write about it, that's one thing. But then to see it full scale and to really be able to touch it, that's a whole other thing. It's really amazing, and for me it's especially fantastic.

NARRATOR: With the lift in place, the team pops the Prosecco. But they may be celebrating too soon. They still have to turn all these parts into a working machine.

But why did the ancient Romans go to such lengths to make death theatrical? Some answers are coming from the victims themselves or at least their bones.

In 1993, Austrian archaeologists uncovered a cemetery in a Roman city, in what is today Turkey. Fabian Kanz, of the Medical University of Vienna, was brought in to analyze the human remains.

FABIAN KANZ: It was a mass grave. We found out that there were remains from 68 people. And 66 have been young males, aged between 20 and 30.

NARRATOR: Unusual injuries offer a clue to who was buried here.

FABIAN KANZ: The distance is about five centimeters.

NARRATOR: These holes in the head, surely the cause of death, were almost certainly the result of a trident, a weapon unique to gladiator combat.

The Roman author Suetonius describes seven gladiator characters, each with different costumes and weapons.

One of the most famous pairings is a Secutor, equipped with a short sword, shield and helmet, and a Retiarius, “the fisherman,” who fought with a net and a trident.

From the forensic evidence, it's obvious who won this battle.

FABIAN KANZ: It was the first known gladiator cemetery. We had in our hands, for the first time, remains of real gladiators.

NARRATOR: Among many of the gladiator bones, Kanz finds something even more remarkable, evidence of healing.

FABIAN KANZ: What was quite surprising for us was the high number of well-healed injuries, which indicates there must be an excellent healthcare for these gladiators.

NARRATOR: Ancient Roman texts offer a clue to one possible treatment, a special potion made from ash.

FABIAN KANZ: And this might have been leaving traces in the bones.

NARRATOR: To find out if there's any truth to this gladiator potion, Kanz grinds a bone sample into a powder, and processes it into a liquid that he puts into an instrument called an “emission spectrometer.”

Here, he sprays the liquid into an argon gas torch, where it burns with a distinctive flame.

FABIAN KANZ: And the color of the flame changes, depending on the elements in the liquid, and therefore, we can find out about the mineral composition of the bone.

NARRATOR: The flame turns from blue to a bright yellow, indicating that the gladiator bone has a high concentration of strontium. Strontium is a natural element with properties similar to calcium, a crucial mineral for building strong bones.

FABIAN KANZ: It was mentioned in the historic texts that a kind of ash drink was substituted to the gladiators to remedy their pain after fighting. And this would perfectly fit to explain the high strontium content of the gladiators.

NARRATOR: Kanz believes gladiators were given the Roman equivalent of calcium supplements to strengthen their bones.

But why go to this trouble to save gladiators? Although slaves, gladiators were trained in special fight schools. The remains of one, the Ludus Magnus, are right in the shadow of the Colosseum.

FABIAN KANZ: The gladiators have been a big investment for the owner of the gladiator school, comparable to modern football or soccer teams. And they wanted to save their investment. And therefore, they just engaged the best available doctors at the time.

NARRATOR: It would have been extremely expensive if half the gladiators were killed at every event. To protect their investment, the Romans began to provide gladiators with medical care, so they could live to fight another battle. And perhaps to compensate the audience for a reduction in the number of deaths, the Emperor added entertainment value by ordering more elaborate stagecraft.

Now, all the major parts of the lift are in place: the cage, capstan and trapdoor.

UMBERTO BARUFFALDI: Now that it's in place, we have to make it work. The first task is installing all the missing pieces.

NARRATOR: They place wheels on the cage, handles on the capstan and, above the capstan, Umberto and Tulio install a spool for rope.

UMBERTO BARUFFALDI: We attach this rope here, and as it turns, the rope wraps around it and pulls the cage up.

NARRATOR: The team connects the capstan to the cage with enough rope to stretch the length of two football fields. Their earlier model is starting to feel very small indeed.

TULIO CLEMENTINI: We only tested the model. That was just 50 kilograms. The real thing is 3,200 kilograms. So that's why things are a bit tense here.

NARRATOR: With everything strung up, Umberto gives the lift a trial run.

He tries to turn the capstan without success. The cage goes nowhere.

UMBERTO BARUFFALDI: Three of us tried to lift it, but it didn't budge, not a bit. It looked like an elephant, impossible to move.

NARRATOR: Umberto calls in reinforcements. Even with six people, they can't turn the capstan to lift the cage or move the trapdoor. It's all too heavy.

GIOVANNI SQUILLACIOTTI: The ramp is very heavy, and the lever system we initially designed does not work.

NARRATOR: Then how did the ancient Romans manage to lift so much weight?

UMBERTO BARUFFALDI: We're facing the same challenges that the Romans had when they were originally making it. The size is the same, the mechanisms are the same, and the problem is just as big.

NARRATOR: Umberto searches for a solution in an unexpected place: Roman ships.

Could the same mechanics that hoisted the heavy sails be used to lift the cage? Umberto's hard drives are filled with images he's collected of surviving pieces of Roman ships. Among them, he finds what may be the key to heavy lifting, a simple device that dates far back in antiquity, the pulley.

The cage weighs 800 pounds. Adding a pulley splits the weight evenly between the two sides of the rope. Another pulley changes the direction of the force. It's easier to pull down than up.

With one pulley attached to the cage, it feels half the weight, only 400 pounds. Attaching two pulleys on the cage makes it feel like only 200 pounds. The more pulleys you add, the more the weight is distributed between them and the less force you need to lift the cage.

UMBERTO BARUFFALDI: The more I worked on this, the more I realized how great the Romans were, and how small we are in comparison. Building the lift, I realized I was learning from them, learning directly from the ancient Romans.

NARRATOR: The team adds pulleys to redistribute the weight of the cage and trapdoor.

Umberto gathers eight men. As they push the capstan, the rope glides through a network of 12 pulleys, and the cage lifts up off the ground.

GIOVANNI SQUILLACIOTTI: The fascinating part is seeing this mechanism, which at first was essentially a static, seemingly simple structure, turn into something dynamic, a machine, simply by using these ropes, pulleys and human strength.

NARRATOR: But can this machine perform the Colosseum's signature magic trick?

To find out, the team wants to release an animal into the world's most famous amphitheater, for the first time in 1,500 years. But which animal?

According to legend, Romulus and Remus, the founders of Rome, were suckled by a wolf. So a wolf is the perfect animal to test the lift.

Paolo Caldora rescues wolves taken as pets and then illegally abandoned. He leads a wolf through the labyrinth of the hypogeum. In ancient times, wild beasts would have been carried in, already in cages.

The cage door is lowered, and the men turn the capstan to raise the wolf. Every part is now working as a synchronized machine. The trapdoor is lowered, the cage rises into place, its door opens, and the wolf emerges into the arena.

The days of wild beasts in the Colosseum as hunters or hunted are, thankfully, long gone, and the wolf runs safely to his rescuer.

Heinz, Umberto and their team have not only re-created an ancient Roman lift machine, they have created a time machine. For a brief moment, raising the wolf opens a window onto the spectacles here in the Colosseum, 2,000 years ago.

HEINZ BESTE: Imagine not just one lift here, but a whole row of them, one behind the other. The corridor was packed with lifts, which produced the spectacular action above.

Now, with the full-scale lift, we can begin to get a sense of just how magnificent the stagecraft must have been. It's really fantastic.

NARRATOR: Each year, over 5,000,000 tourists visit the Colosseum. They are awed by its size and horrified, imagining the slaughter. How could a culture as advanced as Rome justify the spectacular bloodshed that took place here?

KATHERINE WELCH: Gladiatorial games and associated violent spectacles needed absolutely no justification. And in the ancient sources, we find just the opposite, that they were believed to stiffen moral fiber.

NARRATOR: Romans attending the Colosseum were more than spectators, they were participants. These games showcased the power of Rome and reminded citizens that their prosperity was paid for in blood.

MARK WILSON JONES: Inside the Colosseum you have spectacle, you have energy, you have entertainment. The whole building is used as a vehicle for the demonstration of the power of the Roman world and how it came to benefit the populace.

NARRATOR: Though Rome falls to the barbarians in 476, the Colosseum, like a victorious gladiator, still stands. Battered and triumphant, it is a lasting reminder of the gore and the glory of Rome.

Broadcast Credits

WRITTEN, PRODUCED & DIRECTED BY
Gary Glassman
EDITED & CO-PRODUCED BY
Rob Tinworth
CAMERA
Yoan Cart
Antonello Emidi
Mathieu Czernichow
Rob Tinworth
ADDITIONAL DIRECTING
Pascal Cuissot
NARRATED BY
Jay O. Sanders
COORDINATING PRODUCER
Maureen Lynch
ASSOCIATE PRODUCERS
Ben Sweeney
Ana Escobedo
LOCATION PRODUCER
Chiara Messineo
MUSIC BY
Ed Tomney
3D ANIMATION
Doug Quade
ANIMATION
Handcranked Productions
Mitch Butler
VOICEOVER
Caprice Benedetti
Fabrizio Brienza
Michael Cumptsy
Erik Singer
Daniel Stagliano
ASSISTANT CAMERA
Jérôme Lift
Jules Boudon-Chambre
Alessandro Serrano
SOUND RECORDISTS
Daniele Guarnera
Andre Rigaut
LOCATION ASSISTANTS
Alessio di Pasquale
Sara di Vito
MAKE UP ARTIST
Federica Sabatini
BUSINESS AND LEGAL AFFAIRS
Mitchell Silberberg & Knupp LLP
RESEARCH
Scott Tiffany
Allegra Favila
Ben Jones
TRANSLATORS
Juliana Friend
Nicole Gerke
Stephen D. Marth
Verbal Ink
ADDITIONAL EDITING BY
Doug Quade
COLORIST AND ONLINE EDITOR
Rob Tinworth
ADDITIONAL ONLINE EDITING
Dave Bigelow
AUDIO MIX
Heart Punch Studio
GLADIATORS
Brice Lopez
Julien Grellier
Cyril Meot
Regis Deguelle
Damien Montesani
Bain Yoann
Pierre Dufour
WOLF HANDLERS
Paolo Caldora
Paolo Roberto Gianarani
Andrea Cristofori
WOLF
Christal
ORIENTALUX LIFT BUILDERS
Giuseppe Cerroni
Carlo Cerroni
Ennio Cipriani
Antonio Collalto
Mario Coletta
Gennarino D'Andrea
Fabio Di Sabatino
Devid Macerola
Danieli Sandro
BLASI CONSTRUCTION LIFT INSTALLERS
Maricel Blaja
Allessandro Blasi
Allesandru Bochis
Maricel Brici
Ionel Cautis
Giovanni Cavtis
Popa Costica
Severino D'alicandro
Geovanny Zamora De La Cruz
Brici Florin
Massimiliano De Mari
Giuseppe Grasso
Patrizio Lastella
Antonino Parisi
MINGUZZI CRANE COMPANY
Marco Chiossi
Angelo Minguzzi
Giancarlo Minguzzi
Francesco Nitto
Loris Pellizzon
STUDIO MCM LASER SCANNING
Roberto Bonavenia
Francesco Borgogni
Monica Cola
Mauro Papale
LUMBERJACKS
Roberto DiGiovani
Domenico Felli
Luigino Felli
Augusto Lugli
Mimati Vittorio
INTERNS
Marianne Abbott
Maia Chao
Claire Choe
Madeline Coburn
Caroline Fenn
Katherine Hanson
Aleyna LaCroix
ARCHIVAL MATERIAL
bpk, Berlin / Art Resource, NY
Bridgeman Images
Corbis
Getty Images
Smithsonian Institution Libraries, Washington, D.C.
SPECIAL THANKS
Richard Brilliant
Cristiano Brughitta
Ettore Cataldi
Pierluigi Ciprietti
Luigi Colasanti
Ramona Cracas
Roberto Di Giovani
Deutsches Archäologisches Institut
Prof. Stefano Natali
Barbara Nazzaro
Dietrich C. Neumann
Caroline K. Quenemoen
Virginia Sedia
John R. Senseney
Heclilat Ungureanu
Stefano Vellucci
Filming at the Colosseum, the Arch of Titus, the Palatine Hill, and the Roman Forum: su concessione del Ministero per i Beni e le Attivití  Culturali Soprintendenza Speciale per i Beni Archeologici di Roma
Translation of above: Permission from the Ministry of Cultural Heritage and Activities, Special Superintendency for the Archaeological Heritage of Rome.
With grateful acknowledgement to the State of Rhode Island and Steven Feinberg, the Rhode Island Film & Television Office
FOR ZED
EXECUTIVE PRODUCERS
Valérie Abita Manuel Catteau
WRITER/ DIRECTOR FOR FRENCH VERSION
Pascal Cuissot
LINE PRODUCER
Bénédicte Felix
PRODUCTION MANAGERS
Andréa Martinez Raphael Giletti
PRODUCTION ASSISTANTS
Thomas Aboulker Clara Boncorps Mélanie Dumay
FOR ARTE FRANCE
HEAD OF SPECIALIST FACTUALS DEPARTMENT
Hélène Coldefy
NOVA SERIES GRAPHICS
yU + co.
NOVA THEME MUSIC
Walter Werzowa
John Luker
Musikvergnuegen, Inc.
ADDITIONAL NOVA THEME MUSIC
Ray Loring
Rob Morsberger
CLOSED CAPTIONING
The Caption Center
POST PRODUCTION ONLINE EDITOR
Spencer Gentry
DIRECTOR OF PUBLIC RELATIONS
Jennifer Welsh
PUBLICITY
Eileen Campion
Eddie Ward
SENIOR RESEARCHER
Kate Becker
PRODUCTION COORDINATOR
Linda Callahan
PARALEGAL
Sarah Erlandson
TALENT RELATIONS
Janice Flood
LEGAL COUNSEL
Susan Rosen
DIGITAL MANAGING PRODUCER
Kristine Allington
SENIOR DIGITAL EDITOR
Tim De Chant
DIRECTOR OF NEW MEDIA
Lauren Aguirre
DEVELOPMENT ASSOCIATE
Lisa Leombruni
UNIT MANAGER
Ariam McCrary
POST PRODUCTION COORDINATOR
Brittany Flynn
SUPERVISING PRODUCER
Kevin Young
POST PRODUCTION EDITOR
Michael H. Amundson
BROADCAST MANAGER
Nathan Gunner
BUSINESS MANAGER
Elizabeth Benjes
DEVELOPMENT PRODUCER
David Condon
PROJECT DIRECTOR
Pamela Rosenstein
COORDINATING PRODUCER
Laurie Cahalane
SENIOR SCIENCE EDITOR
Evan Hadingham
SENIOR PRODUCERS
Julia Cort
Chris Schmidt
SENIOR SERIES PRODUCER
Melanie Wallace
MANAGING DIRECTOR
Alan Ritsko
SENIOR EXECUTIVE PRODUCER
Paula S. Apsell

FOR NOVA BROADCAST & DVD VERSIONS:

A NOVA production by Providence Pictures, Co-Produced with ZED and ARTE France

© 2015 WGBH Educational Foundation

All rights reserved

This program was produced by WGBH, which is solely responsible for its content.

FOR PBSd INTERNATIONAL/NATIONAL MASTERS:

A Providence Pictures production for NOVA and WGBH Boston in association with ZED and ARTE France

© 2015 Providence Pictures

All rights reserved

IMAGE:

Image credit: (Roman Colosseum)
© Providence Pictures

Participants

Umberto Baruffaldi
Designer/Engineer
Heinz Beste
German Archaeological Institute of Rome
Flavia Campanelli
Structural Engineer
Giovanni Cirillo
Crane Operator
Tulio Clementini
Carpenter
Carmelo G. Malacrino
University of Reggio Calabria
Fabian Kanz
Medical University of Vienna
Adriano Morabito
Roma Sotterranea
Rosella Rea
Director of the Colosseum
Giovanni Squillacioti
Architect/Designer
Katherine Welch
New York University
Mark Wilson Jones
University of Bath

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Petra: Lost City of Stone

How did early engineers carve tombs into rock cliffs and funnel water to this desert city? Airing May 4, 2016 at 9 pm on PBS Airing May 4, 2016 at 9 pm on PBS

Program Description

More than 2,000 years ago, the thriving city of Petra rose up in the bone-dry desert of what is now Jordan. An oasis of culture and abundance, the city was built by wealthy merchants whose camel caravans transported incense and spices from the Arabian Gulf. They carved spectacular temple-tombs into its soaring cliffs, raised a monumental Great Temple at its heart, and devised an ingenious system that channeled water to vineyards, bathhouses, fountains, and pools. But following a catastrophic earthquake and a slump in its desert trade routes, Petra's unique culture faded and was lost to most of the world for nearly a thousand years. Now, in a daring experiment, an archaeologist and sculptors team up to carve an iconic temple-tomb to find out how the ancient people of Petra built their city of stone. Meanwhile, scientists using remote sensors and hydraulic flumes uncover the vast city and its sophisticated water system. The race is on to discover how these nomads created this oasis of culture in one of the harshest climates on Earth.

Broadcast Credits

WRITTEN, PRODUCED & DIRECTED BY
Gary Glassman
ADDITIONAL DIRECTING
Olivier Julien
Scott Tiffany
EDITED BY
Rob Tinworth
CAMERA
Laurent Chalet
Kris Denton
Dan Krauss
Stephen McCarthy
NARRATED BY
Jay O. Sanders
COORDINATING PRODUCER
Maureen Lynch
ASSOCIATE PRODUCERS
Ben Sweeney
Ana Escobedo
LOCATION PRODUCER, CALIFORNIA
Scott Tiffany
SOUND RECORDISTS
Frédéric Heinrich
Steven Bonarrigo
Adriano Bravo
Marla Hettinger
Steve Miller
Ken Pries
Greg Rothschild
ASSISTANT CAMERA
Romain Baudéan
Jerome Lift
Charlie Doan
MUSIC
Ed Tomney
ANIMATION
Handcranked Productions
TIMELAPSE PHOTOGRAPHY
Rob Tinworth
GRIPS
Jan Michalik
Lisa Harding
FLYCAM
et alors productions
Nicolas Turini
Marc Marchand
LOCATION MANAGER
Jihad Hammadeen
PRODUCTION ASSISTANTS
Jairo Brito
Pedro Gomez
Joshua Makela
Gabbah Nawafleh
Khaled Nawafleh
Barakat Nawafleh
LEGAL COUNSEL
Joan Lanigan, Mitchell Silberberg & Knupp LLP
RESEARCH
Anisa Mehdi
Allegra Favila
Elizabeth Ryan
ASSOCIATE RESEARCHER
Shraddha Chakradhar
TRANSLATORS
Jason Reeder
Juliana Friend
ADDITIONAL EDITING
Ryan Shepheard
Irene Su
ADDITIONAL ONLINE EDITING
Jim Ferguson
COLORIST
Michael H. Amundson
AUDIO MIX
Heartpunch Studios
ARCHIVAL MATERIAL
adoc-photos/Corbis
Ulrich Bellwald
boscorelli/Pond5
CORBIS
De Agostini Picture Library / E. Lessing/ Bridgeman Images
Drone Pros
Historical Picture Archive /CORBIS
Miranda Tagliabue Franca
Allison Mickel
MountAiryFilms/Pond5
Thomas R. Paradise
Petra National Trust
Private Collection / Bridgeman Archives
Smithsonian / Getty Images
Jane Taylor/ the Art Archive at Art Resources, NY
Tropical Desert Trips
Vader Video/Pond5
Victoria & Albert Museum London, UK/ Bridgeman Images
Werner Forman / Universal Images Group/ Getty Images
Robert Wenning
SPECIAL THANKS
Ahmad Ashour
American Center of Oriental Research
Talal Ammarin
CFD Consultants International
David Graf
Martha Sharp Joukowsky
Artemis A. W. Joukowsky
S. Thomas Parker
Megan Perry
Petra Archaeological Park
Petra National Trust
Barbara Porter
Royal Film Commission, Jordan
Royal Jordanian Airlines
San Jose State University
Sarah Sharpe
With grateful acknowledgement to the State of Rhode Island and Steven Feinberg, the Rhode Island Film & Television Office
FOR ZED EXECUTIVE PRODUCERS
Valérie Abita
Manuel Catteau
WRITER/ DIRECTOR FOR FRENCH VERSION
Olivier Julien
LINE PRODUCER
Bénédicte Félix
PRODUCTION MANAGERS
Andréa Martinez
Raphaí«l Giletti
POST PRODUCTION ASSISTANTS
Sophie Krykwinski
Rémi Villon
INTERNS
Mélanie Dumay
Clara Boncorps
FOR ARTE FRANCE
HEAD OF SPECIALIST FACTUALS DEPARTMENT
Hélène Coldefy
NOVA SERIES GRAPHICS
yU + co.
NOVA THEME MUSIC
Walter Werzowa
John Luker
Musikvergnuegen, Inc.
ADDITIONAL NOVA THEME MUSIC
Ray Loring
Rob Morsberger
CLOSED CAPTIONING
The Caption Center
POST PRODUCTION ONLINE EDITOR
Spencer Gentry
DIRECTOR OF PUBLIC RELATIONS
Jennifer Welsh
PUBLICITY
Eileen Campion
Eddie Ward
SENIOR RESEARCHER
Kate Becker
PRODUCTION COORDINATOR
Linda Callahan
PARALEGAL
Sarah Erlandson
TALENT RELATIONS
Janice Flood
LEGAL COUNSEL
Susan Rosen
DIGITAL MANAGING PRODUCER
Kristine Allington
SENIOR DIGITAL EDITOR
Tim De Chant
DIRECTOR OF NEW MEDIA
Lauren Aguirre
DEVELOPMENT ASSOCIATE
Lisa Leombruni
UNIT MANAGER
Ariam McCrary
POST PRODUCTION COORDINATOR
Brittany Flynn
SUPERVISING PRODUCER
Kevin Young
POST PRODUCTION EDITOR
Michael H. Amundson
BROADCAST MANAGER
Nathan Gunner
BUSINESS MANAGER
Elizabeth Benjes
DEVELOPMENT PRODUCER
David Condon
PROJECT DIRECTOR
Pamela Rosenstein
COORDINATING PRODUCER
Laurie Cahalane
SENIOR SCIENCE EDITOR
Evan Hadingham
SENIOR PRODUCERS
Julia Cort
Chris Schmidt
SENIOR SERIES PRODUCER
Melanie Wallace
MANAGING DIRECTOR
Alan Ritsko
SENIOR EXECUTIVE PRODUCER
Paula S. Apsell

FOR NOVA BROADCAST & DVD VERSIONS:

A NOVA production by Providence Pictures, Co-Produced with ZED and ARTE France

© 2015 WGBH Educational Foundation

All rights reserved

This program was produced by WGBH, which is solely responsible for its content.

FOR PBSd INTERNATIONAL/NATIONAL MASTERS:

A Providence Pictures production for NOVA and WGBH Boston in association with ZED and ARTE France

© 2015 Providence Pictures

All rights reserved

IMAGE:

Image credit: (Petra)
© Providence Pictures

Participants

Christopher A. Tuttle
American Ctr. of Oriental Research
Sue Alcock
Brown University
Leigh-Ann Bedal
Penn State Behrend
Ueli Bellwald
Archaeologist/Restorer
Cecelia Feldman
UMass Amherst
Nathan J. Hunt
Hunt Studios
Andrew M. Smith II
George Washington University
Thomas M. Urban
Oxford University
Charles Ortloff
Hydraulic Engineer
Thomas R. Paradise
University of Arkansas
Blake Rankin
Hunt Studios

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Hagia Sophia: Istanbul's Mystery

How has this unique structure, built on a seismic fault, survived centuries of quakes? Airing February 25, 2015 at 9 pm on PBS Aired February 25, 2015 on PBS

Program Description

Whether serving as Christian church, Islamic mosque, or secular museum, Hagia Sophia and its soaring dome have inspired reverence and awe. For 800 years, it was the largest enclosed building in the world—the Statue of Liberty can fit beneath its dome with room to spare. How has it survived its location on one of the world's most active seismic faults, which has inflicted a dozen devastating earthquakes since it was built in 537? As Istanbul braces for the next big quake, a team of architects and engineers is urgently investigating Hagia Sophia's seismic secrets. Follow engineers as they build a massive 8-ton model of the building's core structure, place it on a motorized shake table, and hit it with a series of simulated quakes, pushing it collapse—a fate that the team is determined to avoid with the real building.

Transcript

Hagia Sophia: Istanbul's Mystery

PBS Airdate: February 25, 2015

NARRATOR: Hagia Sophia: for nearly a thousand years, the largest enclosed building on Earth. Its heavenly dome soars 180 feet high, supported by arches that inspire awe to this day for their strength and resilience. When it opened, gold mosaics covered over four acres of its walls and ceilings.

How did ancient builders construct such a magnificent monument?

ROBERT OUSTERHOUT (University of Pennsylvania): There’s nothing practical about Hagia Sophia. It’s all innovation.

NARRATOR: Built nearly 1,500 years ago in Constantinople, modern-day Istanbul, Hagia Sophia has survived clashing empires, by transforming from church to mosque to museum.

JOAN BRANHAM (Providence College): Hagia Sophia carries both the history of Christianity and Islam within its walls.

NARRATOR: Most remarkably, Hagia Sophia has survived centuries of city-busting earthquakes. Did ancient architects actually design an earthquake-proof structure? Or will the next big quake bring Hagia Sophia down?

To find out, a team of engineers is monitoring the building and constructing a giant model, placing it on a hydraulic platform and hitting it with powerful simulated earthquakes.

Can they unlock Hagia Sophia’s seismic secrets before Istanbul’s next big quake?

ESER ÇAKTI (Boğaziçi University): There is always this fear factor, this fear of seeing unexpected collapses.

NARRATOR: Right now, on NOVA: The Mysterious Miracle Building.

Hagia Sophia, completed in the year 537, is one of the most magnificent buildings ever constructed. Its size alone is awe-inspiring. Only the pyramids surpassed it in height for almost a thousand years.

Its ceiling is a glittering golden dome that spans over 100 feet across and soars 180 feet above its marble floors. The Statue of Liberty can fit beneath its dome with room to spare.

How did ancient builders, nearly 1,500 years ago, construct this gigantic dome?

Since its completion, Hagia Sophia has withstood the rise and fall of empires. It has transformed from Christian church to Muslim mosque to secular museum.

JOAN BRANHAM: Hagia Sophia influences a number of mosques, and it became a model for Christian churches, as well. Its innovative, ambitious design and its monumental scale speak to people across cultures, faiths and religions.

NARRATOR: How can one building be a symbol for two different religions and continue to inspire people to this day?

KORAY DURAK (Boğaziçi University): Hagia Sophia is a unique building. There are only a few structures in the world that present different layers of history in the last 2,000 years.

NARRATOR: But perhaps the greatest mystery of Hagia Sophia is why it still stands at all. For Hagia Sophia is in Istanbul, known as Constantinople in ancient times. The city straddles two continents, Europe and Asia, and a major earthquake fault. Over the last century, the North Anatolian Fault has unleashed a series of quakes.

The most recent, in 1999, was just 60 miles from Istanbul. And it was devastating, leveling hundreds of buildings across the city, and killing thousands of people.

MUSTAFA ERDIK (Boğaziçi University): The damage caused by the ’99 earthquake is extensive. And plus, there is a huge human loss, about…we lost about 17,000 people.

NARRATOR: But somehow, Hagia Sophia is still standing. In fact, Hagia Sophia has withstood every major earthquake for nearly 1,500 years.

What is the secret to its survival?

As Istanbul braces for the next big one, a team of engineers searches for answers by building an enormous scale model and hitting it with a series of simulated earthquakes. In the process, they will uncover the building’s strengths, and weaknesses, weaknesses that could ultimately threaten Hagia Sophia’s survival.

Eser Çakti is Director of the Earthquake Engineering lab at Boğaziçi University. She is tasked with monitoring the structural integrity of Hagia Sophia.

Slanted floors and leaning columns may appear alarming, but Çakti is most concerned about Hagia Sophia’s core structure. That core structure comes down to a few key elements: the enormous dome, resting on four huge arches, which, in turn, are buttressed by four giant piers and two semi-domes.

Of particular concern are the four arches. If any fail, the dome could collapse. To monitor the arches, her team has placed sensors at strategic points. The sensors can detect the faintest of movements.

ESER ÇAKTI: The data that we obtain from here, is very important in terms of understanding the general structural behavior of this huge building.

NARRATOR: This information is transmitted to screens at Istanbul’s Earthquake Center. Each of the multicolored lines represents vibrations detected by a motion sensor. Normally, the lines are nearly flat, but when an earthquake strikes, there’s a dramatic spike.

From results of years of monitoring, Çakti sees two places of potential danger.

ESER ÇAKTI: These are the vertical vibrations on top of the arches on the east and west side.

NARRATOR: Two of the great arches are moving more than they have in the past, which could have serious implications for the future.

ESER ÇAKTI: If an earthquake comes strong enough, I think there is a real chance it can receive damage.

NARRATOR: Will the next big quake finally topple Hagia Sophia? To investigate what danger Hagia Sophia might be in, Çakti is turning to a tried and true technique, a seismic shake table test.

It’s worked before. In 2012, Çakti teamed up with engineering team Eren Kalafat and Korhan Oral to analyze the structural integrity of the Mustafa Pasha mosque, in Macedonia. They built this large-scale model, placed it on a motorized steel platform, then shook it violently to simulate an earthquake.

The idea is that wherever damage appears on the model, is where damage would appear on the actual building, giving engineers important insights to protect the real structure.

While it may have worked for the Mustafa Pasha mosque, will it work with Hagia Sophia, a building larger, heavier and more complex?

The model team has doubts.

MODEL TEAM MEMBER: I’m afraid of not being able to build it at all. It will collapse while we are building it.

NARRATOR: The main issue is scale. The core structure must be precisely scaled down for the shake table experiment to be accurate. If Çakti chooses a scale of 10-to-1, the dome, at just over 100 feet wide, would be 10 feet wide on the model. But that’s still too big for the shake table.

ESER ÇAKTI: Each shake table has a capacity in terms of its dimensions and in terms of the power that it can create.

NARRATOR: The capacity of this shake table is 10 tons. The scale Çakti wants to use will make the model too big and heavy, so she must scale down her ideas.

After intense recalculations it looks like a 26-to-1 scale could work, at least on paper.

ESER ÇAKTI: We are always nervous at the shake table, whether it will work.

NARRATOR: The scale model is an ambitious project with no guarantee of success, but it pales in comparison to the challenge of building the real Hagia Sophia.

Who built Hagia Sophia, and why?

Hagia Sophia is built at a major crossroad in history: the decline of the Roman Empire and the rise of the Byzantine Empire.

In 324 A.D., after Rome is ravaged by civil war, Emperor Constantine establishes a new capital in the city of Byzantium. It’s renamed after him. He embraces a new religion, Christianity, and Constantinople becomes the center of the Byzantine Empire, as Rome fades in importance.

The Empire thrives, but in the early sixth century, a power struggle erupts, after a new emperor ascends the throne: Justinian. Riots break out, challenging his authority. Theodora, his much younger wife and rumored ex-courtesan, persuades him to fight rather than flee.

ROBERT OUSTERHOUT: Justinian rallied to the challenge. He called the rebels, looking as if he was going to meet their demands, met them in the hippodrome, had the doors closed and had the army slaughter them all.

NARRATOR: Tens of thousands are killed, and Justinian emerges victorious. But during the riots, the rebels burn down much of the city, including an older imperial church, also called Hagia Sophia.

This is all that remains.

ROBERT OUSTERHOUT: Much of the city of Constantinople had been destroyed in the great riots, and this allowed Justinian the opportunity to, in effect, rebuild Constantinople and the church of Hagia Sophia in his own image.

NARRATOR: Justinian needed a building to convey both his power as emperor and piety as a Christian. So what to build?

Joan Branham is a professor of Art History at Providence College and an expert on how builders design sacred space. She is at San Giovanni Evangelista, a church in Ravenna, Italy. Although rebuilt many times, its floor plan dates to when Christianity becomes a state religion.

JOAN BRANHAM: For the first few centuries, Christians worshipped in private, in homes and small buildings. But this completely changes in the fourth century.

NARRATOR: Christianity had been an underground cult and Christians persecuted, but when Christianity becomes the official religion of the Roman Empire, Christians face a different problem.

What should a church look like?

JOAN BRANHAM: Early church builders looked at Biblical prototypes, like the Temple of Solomon described in the Hebrew Bible, but it’s actually a secular Roman building that is adapted for early Christian use.

NARRATOR: That building is the basilica, used for courts of law and other public gatherings. Its floor plan, a large central nave flanked by two aisles and culminating in an apse, becomes the model for churches, an ideal space for worshippers to gather.

Justinian embraces the church’s rectangular shape to demonstrate his Christian piety, but he still needs something to symbolize his imperial power.

He looks to the dome of the Pantheon in Rome, the ultimate symbol of the might and glory of the Roman Empire. But the Pantheon’s dome sits on a thick circular base. Justinian wants his dome to be centered over a rectangular Christian basilica.

JOAN BRANHAM: Justinian sets out to do something that has never been done before. He wanted to merge two architectural structures into a mammoth hybrid space.

NARRATOR: So where do you find builders to create something on a scale that’s never been done before? Justinian turns to Greek mathematicians.

AHMET ÇAKMAK (Princeton University): Justinian hired Anthemius of Tralles and Isidorus of Miletus. Both had experience as mathematicians and physicists and scientists of their day. They were asked to create the most impressive, biggest building ever built.

NARRATOR: Justinian puts these university professors in charge of 100 contractors and 10,000 workers, and gives them the entire treasury of the Byzantine Empire. The emperor is taking a big gamble.

ROBERT OUSTERHOUT: There’s nothing practical about Hagia Sophia. It’s all innovation. It’s geometric flights of fancy, beyond what a practical architect would ever attempt to build.

NARRATOR: Their first challenge is how to support the dome and still keep a huge space for worshippers below.

AHMET ÇAKMAK: If they built walls or columns, the space would not be open like this. It would be much smaller and narrower. In order to make it as large and as heavenly as possible, they need a big space. And that can only be accomplished by building large arches.

NARRATOR: A giant dome will need giant arches to support it.

ESER ÇAKTI: The original architects should have been very concerned about how to support this huge dome over there.

NARRATOR: The team back at the Earthquake Center face the same challenge building their model. Will their arches be strong enough to support the dome?

To find out, they add sacks of cement to simulate the weight of the dome. Each bag weighs about 50 pounds, and they expect the arch should support about 10 of them.

But as the fifth bag is placed…

Luckily, nobody is hurt, as the arch collapses with just over 200 pounds on it.

ESER ÇAKTI: It collapsed before we were expecting the collapse to take place. I think that happened because we didn’t wait for the mortar to set fully.

NARRATOR: While this might seem to be a setback for the team, Çakti insists this kind of unanticipated collapse illustrates one of the main advantages of building a physical model.

ESER ÇAKTI: It is always interesting to see the failure mechanism in real life. When you do it on computers, you develop an idea of how the failure is going to happen, but it is only during a test of this kind, where we see the collapse pattern.

NARRATOR: The slow motion replay of the collapse shows that the downward force of the sacks pushes the arch out sideways.

The weight of the dome exerts the same force on the arches in the real Hagia Sophia.

AHMET ÇAKMAK: The arch wants to push out and fall down. So you have to hold the arch together like bookends.

NARRATOR: To create those bookends, Anthemius and Isidorus, the Greek mathematicians, build four buttress piers, massive weights of brick and mortar, and two semi-domes. These push back against the arches, cancelling out the sideways force caused by the dome.

But Anthemius and Isidorus still have one more problem to solve, how to rest the dome on the tips of the arches.

AHMET ÇAKMAK: The architects had to transition from a circle to a square. This they accomplished by building what is called pendentives. It is this triangular shape that fills in the corners of the square.

NARRATOR: The pendentives, together with the arches, transform the circular base of the dome into a square. And the semi-domes stretch that square into a rectangle.

Justinian has it all: the classic rectangular shape of the basilica, capped by the enormous circular dome.

Anthemius and Isidorus complete Hagia Sophia in only six years, and do indeed spend nearly the entire treasury of the Byzantine Empire.

In 537, Emperor Justinian and his wife, Theodora, unveil their church to the world. All who enter are awed by its size and the richness of its decorations: columns crowned by capitals so finely carved they look like lace. Floors and walls of marble dazzle worshippers with patterns of swirling colors.

ROBERT OUSTERHOUT: Justinian brought marbles from all parts of the empire. The great purple columns that we see in the corners, for example, come from the imperial quarries of Egypt. Elsewhere in the building, we see stones brought from as far away as the Pyrenees, in Spain.

NARRATOR: An eyewitness account reports that the dome looks “as though it were suspended from heaven by a golden chain.”

Like the church before it, Justinian christens this monument, Hagia Sophia, which in Greek means “Holy Wisdom.”

But the dome that Justinian first sees is not the same dome that sits atop Hagia Sophia today. Just 20 years after Hagia Sophia’s unveiling, its dome collapses in a catastrophic earthquake.

ROBERT OUSTERHOUT: We really don’t know what Justinian did when the first dome collapsed. We can imagine he wasn’t very happy. Fortunately for Isidore and Anthemius, they were dead, by that point.

AHMET ÇAKMAK: When the dome collapsed, in 558, the business of rebuilding it was given to the architect Isidorus the Younger, a nephew of the original architect.

NARRATOR: Çakmak believes Isidorus the Younger redesigns the dome. To reduce its weight, he installs 40 windows at its base.

AHMET ÇAKMAK: The windows serve two purposes. One is to get rid of the bricks that you need, which add additional weight, and to let light in.

NARRATOR: Hagia Sophia is put to the test in at least another dozen major earthquakes. The dome suffers two partial collapses, which were repaired, so visitors today cast their eyes up to the same dome built by Isidorus the Younger nearly 1,500 years ago.

But Hagia Sophia has withstood more than just seismic activity. It’s also been resilient to cultural upheavals.

Six-hundred years after Justinian, Constantinople continues to flourish, but its riches inspire envy. In 1204, European Christian Crusaders, on their way to the Holy Land, sack the city and loot treasures from Hagia Sophia to glorify their own churches back in Europe.

Then a new religion challenges the old order: Islam. Its forces lay siege to Constantinople seven times over eight centuries. Finally, in 1453, Sultan Mehmet conquers the weakened city and makes it the capital of his Ottoman Empire.

Mehmet enters the church of Hagia Sophia on a Tuesday, and by that Friday he is praying in the mosque of Hagia Sophia.

ROBERT OUSTERHOUT: For Mehmet the Conqueror, Hagia Sophia was really the ultimate conquest. That was the symbol he was after for his new empire.

NARRATOR: But how can a church become a mosque? From an architectural perspective, it isn’t difficult.

JOAN BRANHAM: There was the addition of the minbar, from which the imam would give the sermon; the mihrab gave the sacred direction orientation to Mecca.

NARRATOR: Later, the Ottomans add large disks calligraphied with sacred words from the Koran, plaster over Christian mosaics, and, outside, construct minarets for the call to prayer.

But Hagia Sophia’s vast dome most easily makes the conversion.

JOAN BRANHAM: The dome itself had religious meaning for both Christian worshippers and now Muslim worshippers; for both, it was a symbol of the heavens.

NARRATOR: The structure at the heart of Hagia Sophia, the round dome on the square base, works as powerfully for Islam as it did for Christianity.

Hagia Sophia is so admired in the Islamic world it becomes the classic model for mosques throughout the Ottoman Empire. But today, Hagia Sophia is a museum, a showcase of its religious and cultural history.

KORAY DURAK: When you enter the building, you look to your left and you see a beautiful mosaic panel from the Byzantine Empire. And you look at your right and you see a wonderful calligraphic quotation from the Koran. You see the history of the whole city, in a sense the whole region, in a nutshell.

NARRATOR: But deciding which layers of its history to display is a battle that continues on its walls.

Stepping onto the battlefield is researcher Hitoshi Takanezawa. He’s on a hunt for Christian mosaics that were plastered over when Hagia Sophia was converted into a mosque. His challenge is how to find the Byzantine mosaics without damaging the Ottoman decorations.

Takanezawa’s secret weapon is this electromagnetic scanner. Normally, it’s used to find structural faults in things like bridges. Nobody has ever used it to find Jesus.

HITOSHI TAKANEZAWA (Kobe Shukugawa Gakuin University): We’re developing new equipment for investigation. It is crucial we find a technology that can deduce whether a mosaic exists, without destroying anything.

NARRATOR: Takanezawa and engineer Satoshi Baba carefully run the scanner against the wall. What might they find?

A tantalizing taste of Hagia Sophia in its full mosaic splendor is here: the church of San Vitale, in Ravenna, Italy, also built during Justinian’s reign, nearly 1,500 years ago.

JOAN BRANHAM: Byzantine visitors would be transported into an entirely different world. And it was through the mosaics that this happened. They were a vehicle to bring the visitor into contact with the Divine.

NARRATOR: That divine glow of Byzantine mosaics is what makes them so awe-inspiring. And the mystery material that gives them that glow is what will help in the search for Hagia Sophia’s hidden mosaics.

Luciana Notturni and Gabrielle Warr are using the same materials to make mosaics today. They begin with glass disks, carefully breaking them into smaller pieces, until they become tiny cubes called tesserae.

Notturni places each tessera, piece by piece into a design she’s drawn on the mortar and carefully angles them to reflect the light.

LUCIANA NOTTURNI (Mosaic Art School of Ravenna): It is believed that, especially in the Byzantine mosaics, the positioning of the tesserae was directly connected to where the light was coming from, so where the windows were, where the main light sources were.

NARRATOR: And to make that light shimmer, they add something else to the mix.

GABRIELLE WARR (Mosaic Art School of Ravenna): It has a thin layer of gold leaf. And the fact that it does have gold in it makes it very reflective and very luminescent.

NARRATOR: The gold tesserae give the Byzantine mosaics a heavenly glow. And, because gold is metal, it may be the key to rediscovering the lost mosaics in Hagia Sophia.

HITOSHI TAKANEZAWA: That design is made by metallic tesseras. So we believe, we hope to find mosaics by our instruments.

NARRATOR: Takanezawa’s scanner sends electromagnetic signals below the surface of the plaster. If the waves strike a buried metal tesserae, they are reflected back, creating an image of the inside of the wall.

HITOSHI TAKANEZAWA: We did this scanning line five times. And this green zone is made of metal tesseras. We can see here the circle design. This is truly made by man’s hand.

NARRATOR: The scanner is working. It has detected a mosaic circle beneath the plaster, but Takanezawa isn’t searching just for circles.

HITOSHI TAKANEZAWA: Now we’ll apply this method at other zones, so maybe it can show some image of the saints or image of the Christ.

NARRATOR: The walls of Hagia Sophia are hiding more than mosaics, they also hold secrets to its seismic strength.

High above the streets of Istanbul, a team is repairing a wall as part of Hagia Sophia’s on-going restoration.

Sonay Şakar is the lead architect.

SONAY ŞAKAR (Ministry of Culture, Turkey): What we’re doing is removing all the cement from the surface you see here. Then we’ll repair the layer of bricks we’ve uncovered.

NARRATOR: Her team must replace crumbling cement from a restoration in the 1950s. She’s using a more resilient mortar, one formulated from the original recipe: limestone, sand, water, and a secret ingredient, ground up brick.

It turns out the best way to preserve Hagia Sophia for the future is to use materials from the past.

SONAY ŞAKAR: The mortar in Hagia Sophia is certainly more flexible than modern mortar, so it adapts to the structural deformations caused by earthquakes.

NARRATOR: The flexibility of the mortar is crucial, but so is how it’s applied.

SONAY ŞAKAR: Hagia Sophia differs from other structures because the layer of mortar is thicker than the bricks.

NARRATOR: Modern brick buildings have thin layers of mortar, but Hagia Sophia’s layers are so thick, they act like cushioning.

Hagia Sophia’s bricks also play a role in earthquake protection.

AHMET ÇAKMAK: Here is an original brick from Hagia Sophia, and here is a modern brick. As you can see, the original brick is significantly lighter than the modern brick.

NARRATOR: Which turns out to be very important.

AHMET ÇAKMAK: If you make the building light, then the building can sway with the earthquakes, like a tree in the wind, flexible but strong.

NARRATOR: Fifteen-hundred years ago, other architects built heavy and massive to protect against earthquakes. Anthemius and Isidorus, the Greek architects, did the opposite. They built light and flexible, the principle of modern seismic engineering. But will this world treasure survive into the future?

Eser Çakti and her team are building a model of Hagia Sophia’s core structure to investigate. Their arch problem solved, they move on to their next challenge: the semi-domes.

They create a mortar that mimics the materials of the real semi-domes and spread it over a wooden mold.

ESER ÇAKTI: We have worked on paper for a long time on how to get it right, how to make it, and then what would be the thickness, what would be the material.

NARRATOR: After the mortar dries, they remove the wooden mold. But as they take off the mold, suddenly a crack appears at the top.

Cracks at this stage mean the semi-dome is clearly too weak for the shake table test. They break apart the semi-dome to get a closer look at the mortar.

KORHAN ORAL (Poligon Yapi): We have four centimeters coming from that side and four centimeters coming from that side. But the failure part was too thin. It is almost a half-centimeter.

NARRATOR: A problem with the way the mortar was applied caused the top of the semi-dome to be much thinner than planned.

ESER ÇAKTI: Some shrinkage occurs after drying of the mortar. We may consider to introduce some elements to the mortar, so that its strength properties will improve.

NARRATOR: The team must rebuild the semi-dome. And they’ll need to come up with a better method for building the final piece of their model, the large, central dome. And that will take some time.

In his hunt for hidden Byzantine mosaics, Hitoshi Takenezawa is heading to the uppermost level of Hagia Sophia, a thin ledge that runs beneath the main arches.

The building is so huge, he must narrow down his search.

HITOSHI TAKANEZAWA: It’s very difficult to decide where we do the research, because this space is a very enormous size. So I have to guess.

Originally, this part was decorated with the figures of saints or archbishops, like there.

NARRATOR: Because these niches on the northern wall are filled with mosaic figures, Takanezawa believes the southern wall may have been too. But have the mosaics survived?

To find out, they run the electromagnetic scanner along the wall.

HITOSHI TAKANEZAWA: We found strong reflections under the plaster. So, we suppose it should be the remains of the mosaics, with 70 percent confidence.

NARRATOR: The team takes a closer look at the scan.

They find metal behind the plaster, but not the gold Takanezawa is hoping for.

HITOSHI TAKANEZAWA: There are only horizontal lines. It would seem it is not a mosaic, but rather a metal structural support.

NARRATOR: Takanezawa’s guess is wrong. No mosaics have survived in this niche.

The challenge is that his scanner measures about two feet at a time, and Hagia Sophia’s surface area is over 200,000 square feet. To narrow down his search, Takanezawa has come to Bellinzona, Switzerland, to explore the state archives.

Inside, archivist Carlo Agliati shows him an astonishing record of Hagia Sophia’s Byzantine mosaics.

CARLO AGLIATI (State Archives of Ticino, Switzerland): In 1847, the Sultan entrusted the architect Gaspare Fossati with the task of restoring the mosque of Hagia Sophia.

NARRATOR: These drawings were made by the Fosatti brothers, Swiss architects who were hired to renovate the aging building, which was then a mosque, in the 1840s.

The Fosattis began stripping plaster from the walls and were astonished by what they found.

CARLO AGLIATI: Fossati’s big discovery during the restoration, hidden under the plaster, was definitely these extraordinary Byzantine mosaics.

NARRATOR: They quickly documented every image before covering them with plaster once again. While some of the mosaics recorded in the drawings have been uncovered, others have never been found.

One, in particular, catches Takenezawa’s eye.

HITOSHI TAKANEZAWA: There is a circular sketch from the Fossati, but the exact location is still the subject of debate.

NARRATOR: The sketch depicts Christ, framed by a cross in a circle. Near Hagia Sophia, the church of Chora contains a strikingly similar image, found in the crown of a dome.

Takanezawa believes the Fossati sketch depicts a similar mosaic in a dome in Hagia Sophia, and he has a hunch where to find it.

HITOSHI TAKANEZAWA: A very plausible hypothesis is that there is a large depiction of the face of Jesus Christ at the top of Hagia Sophia’s immense dome.

NARRATOR: But there’s a problem.

HITOSHI TAKANEZAWA: Currently, it’s covered by plaster and by Koranic verses, but one day, with our scanner, we would like to discover this image. This is my dream.

NARRATOR: It’s a dream Takanezawa could realize, because as part of Hagia Sophia’s ongoing restoration, this enormous scaffold is about to reach the dome.

But if Takanezawa does find Christ beneath the Koranic verse, what should be shown? It’s a question at the heart of Hagia Sophia’s identity, a question with a long history.

AHMET ÇAKMAK: Religiously, it was a Greek Orthodox church. And, during the Fourth Crusade, it was taken over, became a Catholic church. When the Muslims came, they made it into a mosque. Finally, it became a museum, which we thought was a solution to the problem. But unfortunately, the Greeks would like to make it back into a church, and the Muslims would like to make it back into a mosque, and the conflict controversy continues.

NARRATOR: But whether Hagia Sophia remains a museum or is converted back to a church or mosque could prove irrelevant if there is an earthquake. The more pressing question is will it be converted into a pile of rubble?

Eser Çakti hopes the shake table test will provide some answers.

The semi-domes are carefully rebuilt from mortar. But mortar will be too fragile for the main dome, which, like the real thing, will be built from brick.

ESER ÇAKTI: We came to the conclusion that having a brick dome is much easier to construct and it’s more realistic. So dome-wise, I’m confident with what will happen. But with respect to the semi-domes, there I have doubts, because it’s much more fragile.

NARRATOR: Before the test, the seven-ton model must first survive the move to the shake table.

ESER ÇAKTI: This is the largest model ever to be made in our lab. We need to be very careful that, during lift-up, everything should be perfectly horizontal. Otherwise, we may damage the model.

NARRATOR: The model is so heavy it bends the steel plate that supports it, which puts pressure on the structure.

It settles onto the shake table, but has it suffered any damage? As the wooden molds come away, Çakti looks for cracks. If the model breaks at this stage, they will be unable to perform the earthquake test, and months of work will have been for nothing.

ESER ÇAKTI: We have observed some cracks on the semi-domes. But we don’t see them from outside. These are just interior cracks.

NARRATOR: Çakti believes the cracks do not compromise the structural integrity of the model, so the team moves on, installing motion sensors in similar locations as the sensors in the real Hagia Sophia.

ESER ÇAKTI: We will be able to compare the vibrations that we record during the shake table test with those obtained from the real structure.

NARRATOR: The model is a scaled down version of Hagia Sophia’s core structure: the main dome, four great arches, four buttress piers and the two semi-domes. But will the model move on the shake table in a similar way as the real building moves in an earthquake?

Astonishingly, overnight, the sensors get an unexpected trial run: a real earthquake.

ESER ÇAKTI: At about four a.m. we had an earthquake near Istanbul. Its magnitude was 3.6. So, by pure chance, we have now recordings of that earthquake recorded on the model. And we have the same earthquake recorded by our instruments in Hagia Sophia.

NARRATOR: The parallel recordings verify that the sensors on the model and in the real building are reacting in a similar way.

Now it’s time to see how the model will react to a more powerful quake. They calibrate the shake table to simulate the impact of the devastating ’99 earthquake: magnitude 7.4. The duration of the test is scaled down to match the size of the model, about three seconds. The sensors capture every twist and turn.

The model seems to have taken the impact without damage. But what everyone really wants to know is, “How will it stand up to an even stronger earthquake?”

To find out, the team must push the power of the shake table beyond anything they’ve tried before. The simulated quake is measured in Gs, its gravitational force.

ESER ÇAKTI: We are increasing the amplitude of our earthquake one more step, so that now we aim 2.2G.

EREN KALAFAT (Poligon Yapi): You said two was the maximum. Now we are going more than two?

ESER ÇAKTI: If we can do it, we’ll go for 2.4.

EREN KALAFAT: Perfect.

NARRATOR: They hit the model with a simulated earthquake, stronger than any in Istanbul’s’ recorded history.

Çakti checks out the damage.

ESER ÇAKTI: I see one new crack in this arch. But surprisingly, there is nothing new with the semi-domes. We were afraid about them. But they are as they have been before.

NARRATOR: The Hagia Sophia model has survived two enormous earthquakes in quick succession, with minimal damage, but the team isn’t done yet.

ESER ÇAKTI: We have passed the known capacity of our shake table, and then it appears the mechanics have allowed us to go further.

NARRATOR: Can the shake table push the model to the point of collapse?

They hit it with everything they’ve got. At this stage, the model has been hit by the equivalent of a major earthquake every day for a week. And although it teeters on the edge of collapse, it still stands.

ESER ÇAKTI: There are two vulnerable parts: the semi-domes and then the arches. It is just a matter of time to see which one will go first.

NARRATOR: With everyone’s eyes on the semi-domes and arches, nobody anticipates what happens next. The great dome comes crashing down.

ESER ÇAKTI: I am a little bit surprised, now, because I would have expected the main arch to go, and then instead of the main arches, the main dome went.

NARRATOR: The slow motion replay reveals that the semi-domes separated from the structure, and with the main arches damaged, support for the dome was severely compromised.

KORHAN ORAL: My masterpiece is collapsed now, but, for scientific observation, I can accept it.

ESER ÇAKTI: Now we have come to its end. But, at the same time, we know that we have lots of things to do in terms of data analysis and interpretation. This is a little bit frightening, but it needs to be done.

NARRATOR: It is too early to draw any firm conclusions, but the model going 15 rounds against the most powerful simulated earthquakes the shake table could produce explains Hagia Sophia’s supposedly miraculous survival.

ESER ÇAKTI: If there is a miracle, it is in its design. It was constructed to survive. The balances between its structural elements appear to create a dance. The domes, arches, semi-domes, buttress piers, they behave in harmony.

NARRATOR: Though the model lies in ruins, Çakti believes the data captured in this experiment will provide new insights into Hagia Sophia’s structural strength and how it can be preserved for the future.

ROBERT OUSTERHOUT: Scientists have spent decades trying to analyze the structural system of Hagia Sophia. But when you go inside Hagia Sophia today, you don’t see structure. We’re not meant to understand how the great dome is supported. We see only the weightless quality of the building. That was what was most important. We understand the interior of the building as an experience that’s completely different from anything else on Earth.

NARRATOR: After nearly 1,500 years, Hagia Sophia continues to astonish modern engineers with its ancient secrets of seismic engineering and its resilience, not only as a building, but also as the proud expression of great civilizations that have adopted it as a symbol.

SONAY ŞAKAR: We don’t think of Hagia Sophia based on the meanings other people assign to it. Hagia Sophia has an identity of its own. It is a monumental building; it is a special building. Our goal is to pass it down to the next generations.

NARRATOR: Hagia Sophia will have to endure many more shifts in the ground that lies beneath it and the cultures to which it is entrusted. Hopefully, its majestic beauty and innovative design will inspire people of all religions and cultures to protect it for generations to come.

Broadcast Credits

WRITTEN, PRODUCED & DIRECTED BY
Gary Glassman
CO-PRODUCED & DIRECTED BY
Larry Klein
ADDITIONAL DIRECTING
Olivier Julien
Rob Tinworth
EDITED BY
Rob Tinworth
CAMERA
Laurent Chalet
Matthieu Czernichow
Oytun Orgul
Yoan Cart
Rob Tinworth
NARRATED BY
Jay O. Sanders
COORDINATING PRODUCER
Maureen Lynch
ASSOCIATE PRODUCER
Ben Sweeney
Ana Escobedo
VOICEOVER
Caprice Benedetti
Gamze Ceylan
Jun Naito
Erik Singer
MUSIC BY
Ed Tomney
ANIMATION
Handcranked Productions
ASSISTANT CAMERA
Jérôme Lift
Jérôme Telo
SOUND RECORDISTS
Frédéric Heinrich
Oguz Kaynak
Erkal Taskin
GAFFER
Mehmet Tuna
FLYCAM
Et alors Productions
Nicolas Turini
Marc Marchand
LOCATION MANAGERS
Zeynep Santiroglu Sutherland
Saygin Saral
Chiara Messineo
PRODUCTION ASSISTANTS
Giacomo Banchelli
Yusuf Genel
RESEARCH
Chris Cassel
Maggie Lange
LEGAL COUNSEL
Mitchell Silberberg & Knupp LLP
TRANSLATORS
Emre Ersolmaz
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Ayako Takase
ADDITIONAL EDITING
Brian Truglio
COLORIST
Ryan Shepheard
ADDITIONAL ONLINE EDITING AND COLOR CORRECTION
Jim Ferguson
AUDIO MIX
Heart Punch Studio
INTERNS
Marianne Abbott
Maia Chao
Claire Choe
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Caroline Fenn
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Benjamin Jones
Aleyna LaCroix
ARCHIVAL MATERIAL
The Bridgeman Art Library
The Bridgeman Art Library/Getty Images
Corbis Images
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Panoramic Images/Getty Images
SuperStock/Getty Images
Universal Images Group/Getty Images
SPECIAL THANKS
Andrei Reinhorn
Michael Constantinou
Department of Civil, Structural and Environmental Engineering at the University of Buffalo
Hayrullah Cengiz, Director of Hagia Sophia, Turkish Ministry of Culture
Anne McClanan
Matthew Savage
Poligon Yapı
Ulus Yapı
With grateful acknowledgement to the State of Rhode Island and Steven Feinberg, the Rhode Island Film & Television Office
FOR ZED
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Musikvergnuegen, Inc.
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SENIOR PRODUCERS
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FOR NOVA BROADCAST & DVD VERSIONS:

A NOVA production by Providence Pictures, Co-Produced with ZED and ARTE France

© 2015 WGBH Educational Foundation

All rights reserved

This program was produced by WGBH, which is solely responsible for its content.

FOR PBSd INTERNATIONAL/NATIONAL MASTERS:

A Providence Pictures production for NOVA and WGBH Boston in association with ZED and ARTE France

© 2015 Providence Pictures

All rights reserved

IMAGE:

Image credit: (Hagia Sophia)
© Providence Pictures

Participants

Carlo Agliati
State Archives of Ticino, Switzerland
Joan Branham
Providence College www.providence.edu/art/history/branham.htm
Ahmet LJakmak
Princeton University
Eser LJakti
Boğaziçi University
Koray Durak
Boğaziçi University
Mustafa Erdik
Boğaziçi University
Luciana Notturni
Mosaic Art School of Ravenna
Korhan Oral
Poligon Yapı
Robert Ousterhout
University of Pennsylvania
Sonay Şakar
Ministry of Culture, Turkey
Hitoshi Takanezawa
Kobe Shukugawa Gakuin University

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