Petra: Lost City of Stone
How did early engineers carve tombs into rock cliffs and funnel water to this desert city?
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. (Premiered February 18, 2015)
Petra: Lost City of Stone
PBS Airdate: May 4, 2016
NARRATOR: It's one of the most magnificent cities of the ancient world: Petra. Its monumental temple-like tombs soar over a hundred feet tall. And these wonders of design and engineering are not constructed, they're carved out of sandstone cliffs.
At its height, Petra was the center of a vast trading network in frankincense and myrrh, treasures of antiquity. It was home to over 30,000 people, in one of the most bone-dry deserts on Earth.
UELI BELLWALD (Archaeologist/Restorer): It is not an appropriate location for a city. There is not even drinking water down there.
NARRATOR: How, over 2,000 years ago, did an ancient people supply enough water for this vast city? And how did they carve these magnificent structures so high up in these cliffs?
To find out, a geoscientist teams up with stonemasons to carve a Petra-style tomb.
TOM PARADISE (University of Arkansas): We're looking at something that hasn't been witnessed for almost 2,000 years.
NARRATOR: And archaeologists and hydro engineers discover how a group of nomads transformed this desert city into an oasis, making Petra the Las Vegas of the ancient world.
LEIGH-ANN BEDAL (Penn State Erie, The Behrend College): It is really conspicuous consumption of this precious resource, water, in this desert environment.
NARRATOR: Finally, after 2,000 years, the secrets of Petra are about to be revealed. Up now, on NOVA, Petra: Lost City of Stone.
It's one of the driest places on Earth. Yet concealed among the canyons of this harsh desert, in the Kingdom of Jordan, is a magnificent ancient city: Petra. For over a thousand years, its location remained hidden, protected by fortress-like cliffs and Bedouin tribes who fiercely guarded its secret.
Then, in 1812, a Swiss adventurer, disguised as an Arab pilgrim, risks his life to search for the legendary city. Johann Ludwig Burckhardt makes his way through the Siq, a dramatic canyon rising almost 600 feet that twists and turns for nearly a mile. Near its end, the canyon widens to reveal a towering temple-like facade. It is called the Treasury, or “Khazneh,” in Arabic.
Built 2,000 years ago, it is a masterpiece of design and engineering. Majestic columns rise from the canyon floor, topped by ornately carved capitals; statues of mythological figures adorn its facade; a fanciful urn graces its roof; and a towering doorway leads inside to a room with three chambers. Here, there is no elaborate carving, just the simple, natural beauty of the stone.
TOM PARADISE: And then we back away, and we realize, not only is this building unique and fantastic, but it has been carved into the sheer face of living rock.
NARRATOR: The Treasury is actually a sculpture on a monumental scale. At 80 feet wide and 127 feet tall, it is twice the height of the Mt. Rushmore memorial.
As Burckhardt continues through the canyon, he discovers hundreds of magnificently carved facades everywhere, many rivaling the grandeur of Egypt, Greece and Rome. But there is more: the ruins of an entire city, a 6,000-seat theater carved right out of the sandstone; a main street lined with huge temple-like structures; and even more spectacular monuments carved higher in the mountains.
But Burckhardt's re-discovery of the legendary city sparks more questions than answers. Who built Petra and why?
Burckhardt was inspired by stories of a mysterious desert tribe who gained their wealth trading spices and silks among China, India, Egypt and Rome and then hid their treasures of gold in the cliffs.
Greek and Roman sources provide a name for these people: the Nabataeans. An account from the fourth century B.C.E. describes the Nabataeans as nomadic tent-dwellers, but three centuries later, another source describes them as a sophisticated people, inhabiting a prosperous city.
Around the time of Jesus, Nabataea is a thriving kingdom surrounded by Egypt, Judea and the vast north Arabian Desert. How, in just a few centuries, did a village of tents become a wealthy kingdom, and how, in the middle of a desert, did they build Petra?
Tom Paradise has spent over three decades trying to find out. He is a geoscientist who specializes in preserving ancient structures.
Alongside the Treasury, he sees strange square marks that could be a clue to how it was built. Are these marks the remnants of where an ancient scaffold was anchored to the cliff face?
TOM PARADISE: For many years people considered these to be holds for wooden scaffolding that may have been used for the actual carving.
NARRATOR: But Paradise has doubts. If these are scaffolding marks, why did the Nabataeans leave them here? And why are they found nowhere else in Petra?
Paradise believes the real reason for the marks may be tied to the fanciful name given to this monument centuries ago.
TOM PARADISE: This building is called the Khazneh. It is the Treasury, and so legend goes back millennia that this housed riches.
NARRATOR: Because it is known as the Treasury, people have searched it for treasure. Bullet holes riddle the urn at the top. And these marks may be footholds to climb up and get a closer look.
TOM PARADISE: We think maybe those footholds were carved for the purpose of raiding the upper parts of the Khazneh looking for the treasure.
NARRATOR: But the urn holds no gold; it's solid rock. The only treasures here are the magnificent sculptures. Whatever the true purpose of these marks, Paradise is certain they're not for scaffolding. After all, in this desert, wood is relatively scarce.
So how on earth could the ancient Nabataeans carve such a huge monument so high up in the cliff face without scaffolding?
Paradise has a bold plan to find out. Working with a team of stonemasons, he will carve a Nabataean-style facade for the first time in 2,000 years.
TOM PARADISE: I may be sitting on the answer to the age-old question as to, “How were these facades carved?”
NARRATOR: At the same time, archaeologists and hydro engineers are investigating how the Nabataeans could even survive in this bone-dry environment.
UELI BELLWALD: The entire hydraulic infrastructure was built, as I think I may prove, following one master plan.
NARRATOR: Their groundbreaking discoveries are revealing the engineers of Petra were not only masters of stone but also of water, transforming a desert city into the Las Vegas of the ancient world.
Now, can scientists finally uncover how a nomadic tribe built this city of stone and why Petra ultimately vanished into legend?
Many people will recognize the Treasury from the climactic scene of Indiana Jones and the Last Crusade, where Harrison Ford and Sean Connery enter a secret temple to discover the Holy Grail. But despite the great Hollywood story, the Treasury and most of Petra's iconic buildings are not temples, they're tombs.
The Nabataeans left very little writing, but on some of their facades are inscriptions in an Aramaic script, the common language of the Middle East in the time of Jesus.
This one, on a facade called “Turkmeniya” reads in part: “This tomb is sacred. Nothing of all that is inside shall be changed or removed forever.”
Tomb raiders disregarded notices like this, so human remains and grave goods rarely survive, but body-sized niches leave no doubt these were burial chambers. In all, the cliffs of Petra hold over 800 tombs.
CHRISTOPHER A. TUTTLE (American Center of Oriental Research): The prominence of these monuments led many of the early explorers to consider the possibility that this might just be a city of the dead, a necropolis. But over the past 200 years, all of the research has actually shown it was a city of the living, as well.
NARRATOR: Chris Tuttle has been working here for more than 10 years. Although less than two percent of the site has been excavated, archaeologists have mapped and surveyed the area. All in all, ancient Petra was a metropolis about the size of the island of Manhattan. There is a two-square-mile downtown where people lived, worked and prayed.
Suburbs housing more people stretch to the north and south. Based on these surveys, Tuttle can estimate the population.
CHRIS TUTTLE: At its height, we expect this city housed somewhere between 20,- or 30,000 people.
NARRATOR: Yet unlike cultures that bury their dead in isolated areas, in Petra, tombs are everywhere. Why did the Nabataeans carve their tombs throughout the city? And how did they do it?
Paradise hopes his carving project will provide some answers.
TOM PARADISE: Creating an experiment in which we reconstruct a facade will give us insight into how the Nabataeans carved these fantastic facades 2,000 years ago.
NARRATOR: But Paradise can't carve his facade here; Petra is a protected World Heritage Site. He must find a cliff face with the right kind of sandstone somewhere else.
His search takes him a world away, to Southern California.
NATHAN J. HUNT (Hunt Studios): This looks like a promising prospect.
NARRATOR: While the ocean view is a sharp contrast to the Jordanian desert, the sandstone is identical to Petra's.
Paradise enlists stonemasons Blake Rankin and Nathan Hunt. With permission from the landowner, they search for just the right rock.
Hunt is a classically trained master carver and architectural sculptor with over 18 years of experience.
NATHAN HUNT: We're looking for a fine-grained sandstone, which lends itself to ornamental carving.
NARRATOR: Sandstone is a soft rock made of compressed layers of sand and minerals.
BLAKE RANKIN (Hunt Studios): That looks like the type of stone we're looking for. Yeah, this is great. It looks like it's going to carve really well.
NARRATOR: The team has found the perfect rock and cliff face. Now, they must find the right tools for the job.
Back in Petra, Paradise discovers a clue in the stone: chisel marks made from iron tools.
TOM PARADISE: The technology used with chisels in stonework haven't changed in 2,000 years. We use the same chisels, and so they leave the same marks.
NARRATOR: By matching modern day tool marks with those found in Petra, their adviser, Tom Paradise, tells them exactly which tools to use: the claw, the flat chisel and the pointed chisel.
TOM PARADISE: The pointed chisel is used for the coarser chiseling that removes large amounts of rock.
NARRATOR: So the pointed chisel is exactly what Hunt and Rankin use to begin work.
BLAKE RANKIN: Yeah! It feels good to be carving.
NARRATOR: But their exuberance fades fast. Carving by hand is seriously slow.
NATHAN HUNT: There's no way we can do it by hand.
NARRATOR: A Greek source says the Nabataeans had few slaves. They probably did have plenty of skilled manpower and time. Hunt and Rankin have neither, but they have power tools.
Even so, Rankin insists they're not cheating.
BLAKE RANKIN: This is a chisel very similar to one that the Nabataeans would have used. The only difference is that we've mechanized the hammer process so that we can move a lot of stone really quickly.
NARRATOR: The carvers have found the right rock and the right tools for the job. As Hunt and Rankin prepare the cliff face, Paradise must decide what exactly to carve.
What makes a Nabataean tomb Nabataean?
Many of the facades in Petra actually look like they belong somewhere else. At the Treasury, Paradise finds statues, columns and capitals reminiscent of ancient Greece and Rome. And across Petra, he finds architectural features from other far-flung empires: a step design associated with Assyria and Mesopotamia, elephant-headed capitals evoking India, even Egyptian obelisks. But, among the familiar, are designs Paradise has seen nowhere else.
TOM PARADISE: There is a pediment at the top that is split in the middle, capped by a cone, a capital and an urn at the top. This isn't Greek. This isn't Roman.
NARRATOR: This new design is seamlessly mixed with features from far-off cultures.
TOM PARADISE: The architecture is this synthesis. And this begins to tell us a story that is the real Petra.
NARRATOR: What makes a Nabataean tomb Nabataean is the combining of their own unique style with designs from other empires. But how did these people in the middle of the desert come into contact with such faraway places?
Two words: “frankincense” and “myrrh.” Frankincense and myrrh were must-have luxury items in antiquity. In the New Testament, they are among the gifts the Three Kings bring to the baby Jesus.
Made from dried sap from trees in the southern Arabian Peninsula, they were burned obsessively in religious ceremonies in Egypt, Greece and Rome. But to get that incense to consumers throughout the Mediterranean, it first had to be transported through the desert.
After centuries of living as nomads, the Nabataeans knew every secret source of water. If you wanted to cross the desert and make it out alive, you had better have a Nabataean leading the way.
Along the route, they built outposts to guard their goods and extract a toll. In a valley, just over the mountain from Petra, Andrew Smith has excavated this fort, called Bir Madhkur.
ANDREW M. SMITH, II (The George Washington University): There was definitely a Nabataean presence here, most likely related to the trade that came out of Petra.
NARRATOR: Among the artifacts he excavated are dozens of tiny clay perfume bottles.
ANDREW SMITH: The Nabataeans were most likely processing some of the raw frankincense. And they would have bottled and then packed them tightly, so that they weren't going to break, and probably loaded them on camels or even donkeys.
NARRATOR: The Incense Road became the lifeblood of the Nabataeans, pulsing from Saudi Arabia to the Port of Gaza, the gateway to Greece and Rome. The financial reward from this trade catapults a desert tribe into a powerful kingdom. Nabataean towns and tombs spring up throughout the northwestern Arabian Peninsula.
By the first century, the Roman writer Pliny called the Nabataeans “the richest race on Earth.” Much of their wealth went into building their capital city, Petra.
Tom Paradise believes the Nabataeans far-flung trade connections influenced their domestic designs.
TOM PARADISE: Because Petra is a crossroads for the region, it makes sense that they would adopt and adapt different architectural styles from a lot of their trading partners.
NARRATOR: But with all these different styles, what should Paradise pick for his carving experiment?
TOM PARADISE: This sort of facade represents more than 500 other facades in Petra. So this style really is the archetype of the tomb facades.
NARRATOR: To Paradise, this tomb is typically Nabataean. Although it appears plain, it's a mash-up of different architectural styles. It has the remains of a Greco-Roman doorway, Nabataean capitals, an Egyptian cornice and a design from Assyria that may represent a stairway to heaven, called a “crow step.”
But when the carving team transfers the design to California, it isn't wide enough to fit the rock.
NATHAN HUNT: You never really know how it's going to work in the stone until you get started.
BLAKE RANKIN: We think it's going to look a lot better if we widen the facade.
NARRATOR: But how will making the facade wider affect the design?
TOM PARADISE: Make each block of the crow step seven by seven inch.
NATHAN HUNT: This would be the edge of the crow steps.
BLAKE RANKIN: That would be great.
NARRATOR: Grappling with this problem, the team may shed light on a mystery that has confounded scholars for decades: why do Nabataean tombs, while similar, have unique variations?
TOM PARADISE: There is one motif they modify a lot, and that is the crow step. Why the difference? We have never really understood.
NARRATOR: Some of the tombs in Petra have crow steps that reach all the way down to a narrow ledge called the cornice. Other crow steps meet in the middle. Some scholars have argued this reflects an evolution in design, but Paradise thinks they have struck upon a practical reason.
TOM PARADISE: As we make the facade wider, it really requires us to take the crow steps all the way down to the cornice.
NARRATOR: If the facade is wider, the crow steps must break apart.
TOM PARADISE: Increasingly, we notice that changes of the rock actually caused changes within the design elements. I think we have to give more credit to the rock than we have in the past.
NATHAN HUNT: Just sort of roughly mark nine inches on there.
NARRATOR: By carving their own facade, they discover a basic principle of Petra: the rock influences what they carve and where they carve it.
But why here? Choosing to build their capital in the middle of a rocky desert poses another age-old question: how did the Nabataeans get enough water to support such a magnificent city?
One clue is here, in the city center, at a structure known as the “Great Temple.” Its monumental stairway leads to a large stone platform, surrounded by over a hundred columns. Holes in the courtyard show there are channels running underneath it.
Sue Alcock leads a team from Brown University to investigate.
SUE ALCOCK (Brown University): If we could make all this surface architecture go away, you know, just, kind of like magically, lift it up and look down, I think we would see quite a network of these channels and canals.
NARRATOR: She may be short on magic, but Alcock does have another way to look below the surface, a technology called G.P.R., ground-penetrating radar.
THOMAS M. URBAN (University of Oxford): Excavation is inherently destructive. This is a way to get a look at what is down there, in the same way you would go in for an X-ray, perhaps, before you went in for a surgery.
NARRATOR: The radar sends a high-frequency radio wave into the ground. When the wave passes through different materials, like from stone to soil, part of the wave is reflected back. But the speed of the wave changes depending on the material, slower for soil, faster through air. Detecting these changes is how the G.P.R. “sees” where the channels are.
The team systematically drags the radar back and forth across the courtyard.
TOMMY URBAN: There's some kind of a channel, right there.
SUE ALCOCK: Oh, yeah, look at that.
NARRATOR: Beneath the Great Temple is a network of channels that looks like plumbing. Intriguingly, the channels seem to extend beyond the courtyard.
SUE ALCOCK: When we look at Petra, we often tend to think about building by building, and, actually, I think it was all tied together.
NARRATOR: Alcock believes these channels are evidence of a massive citywide water system.
SUE ALCOCK: Petra was an urban center, and it had urban water supply.
NARRATOR: There's just one problem with this theory. Petra is in one of the driest places on the planet. If the Great Temple is indeed the heart of a vast engineering system that supplied an entire city with water, where is all that water coming from?
One possible source is still used, daily, by locals. It's called “Ain Musa,” or the “spring of Moses.” Allison Mickel and Cecelia Feldman, of Brown University's survey team, join hydro engineer Charles Ortloff to investigate.
CECELIA FELDMAN (University of Massachusetts, Amherst): In Numbers 20:11, it talks about how the Israelites were wandering in the desert, and Moses strikes this rock, in fact, in anger, and water flows forth.
NARRATOR: The story of Moses miraculously bringing forth water has been linked in legend to this rock and spring. But it would take an engineering miracle to get this water from Ain Musa to Petra's city center. It's five miles away.
In the Siq, the entrance to Petra, the team finds evidence for how the water may have been brought here. Running along the side of the path is a narrow channel which has imprints of what were once enclosed ceramic pipes.
CHARLES ORTLOFF (Hydraulic Engineer): If you look inside of the channel, you can see the actual imprints of ceramic sections that are roughly about a third of a meter long.
NARRATOR: At roughly a foot long, it would require tens of thousands of segments to create a five-mile pipeline from Ain Musa, high in the mountains. And every one of those joints would have the potential to spring a leak. Could the Nabataeans possibly have pulled off such a feat of hydro engineering?
At California State University in San Jose, Charles Ortloff and graduate student Shayan Mirzahosseini are trying to figure that out, using this 26-foot tank.
CHARLES ORTLOFF: Water is extremely precious to the Nabataeans, so ancient engineers needed to design a pipeline that would be free of leaks.
NARRATOR: Their challenge, and Ortloff's, is how to get water to flow through a pipe as quickly and efficiently as possible.
CHARLES ORTLOFF: The different angles represent different choices.
NARRATOR: One choice seems obvious: make the slope of the pipe steep.
Ortloff sets the slope to six degrees and turns on the water.
Things start out well. The water is flowing fast. But it fills the pipe too quickly, producing an area of turbulence called a hydraulic jump, which causes the water flow to slow down.
CHARLES ORTLOFF: This is the hydraulic jump, right here.
NARRATOR: But there's a bigger problem. The pipe is now filled with water, raising the pressure. In the ceramic pipelines, that pressure could create leaks at the joints.
CHARLES ORTLOFF: So that design, where we have the steeper slope, is not good.
SHAYAN MIRZAHOSSEINI: Okay, closing all the valves.
CHARLES ORTLOFF: If you can put the brick on the other side of this, we're just going to slide it over.
NARRATOR: Ortloff adjusts the slope of the pipe to four degrees.
CHARLES ORTLOFF: Little more, little more. There we go. Got it.
NARRATOR: A small change in the slope, just two degrees shallower, has a big impact on the speed of the water.
CHARLES ORTLOFF: The big surprise here is that we have only changed the slope by two degrees, and yet we have a completely different flow pattern.
NARRATOR: The flow is fast. And, in this test, the pipe never completely fills with water, which would be good news for Petra's plumbers.
CHARLES ORTLOFF: The entire flow has an exposed air space above the surface, and this will prevent leakage in the system.
NARRATOR: With the help of modern day tools, Ortloff has shown that the best design for delivering water fast and leak-free is a four-degree slope.
And when Ortloff measures the angle of the carved channel in Petra, he makes a remarkable discovery.
CHARLES ORTLOFF: If we look at actual field measurements, we're able to see that, with their pipeline, the ancient Nabataean engineers had a slope of approximately four degrees.
NARRATOR: Two-thousand years ago, Petra's engineers worked out the perfect design for their long-haul pipelines.
CHARLES ORTLOFF: They invented scientific principles that were only officially discovered, in the west, some 2,000 years later.
NARRATOR: It is clear that the Nabataeans were master hydraulic engineers. But water is not the only scarce resource in the desert. Wood from local trees was also in short supply. So how could the Nabataeans build their tombs so high up in the cliff face without using large wooden scaffolding?
Paradise finds an important clue in this unusual carving, aptly called “The Unfinished Tomb.”
TOM PARADISE: The top is finished. The upper area of the capitals remains somewhat crude and still in progress. But then, below that, nothing has been carved at all. It's the natural sandstone face.
NARRATOR: To Paradise, the progression of finished at the top and barely started below, can mean only one thing.
TOM PARADISE: The Nabataeans started from the top and carved down.
NARRATOR: The unfinished tomb shows that Nabataeans began by sculpting the top layer of the facade, and then worked their way down the cliff face.
NATHAN HUNT: Getting windy again.
BLAKE RANKIN: Yup.
NARRATOR: Back in California, Paradise tells Hunt and Rankin they must carve their facade Nabataean style: top-down and without scaffolding.
NATHAN HUNT: There's a lot of challenges involved in trying to figure out how the Nabataeans carved a piece like this. I die like a Nabataean is my worst fear: falling off the rock!
NARRATOR: Up to now, they've been using safety harnesses. But the Nabataeans top-down approach gives them an ingenious idea for how to carve without harnesses or a large wooden scaffold.
BLAKE RANKIN: We have drilled into the stone here and placed a couple of pins and then put a plank on top and created a temporary and movable ledge that doesn't require a lot of material.
NARRATOR: They drive three pins into the rock, and lay just a couple of planks of wood across them, forming a platform. As their carving descends, it erases the holes they've made, leaving no sign of their platform.
NATHAN HUNT: So, by the time we get to the bottom we have pretty much removed all evidence of any plank.
NARRATOR: The pin and plank solution works perfectly. It could explain how the Nabataeans were able to carve so high up without scaffolding, and why no evidence for the technique can be found.
Halfway through the carving, the team makes another discovery.
BLAKE RANKIN: We can move a lot of stone really quickly with these chisels. We've been moving a surprising amount of stone every day.
NARRATOR: A little carving creates a lot of rubble.
TOM PARADISE: I really cannot believe that much carving produced this much rubble.
NARRATOR: The rubble has formed a ramp. This means they don't need their platform anymore. Now, they can just walk up to the facade.
TOM PARADISE: When we see this much material being produced from the carving, we now realize that we create ramps from this rubble that gives you access to the facade for the stone-carvers.
NARRATOR: Combining the clues found in Petra with the discoveries in the carving project, a new theory emerges for how the Nabataeans may have carved the Treasury. They begin by climbing to the top. Here, they cut a narrow ledge into the cliff face. Using ancient drills, they fix pins below the ledge and lay planks across to provide a platform for the carvers. The first thing they carve is the urn and the upper layer of the monument. They work their way down, sculpting the split pediment and the magnificent statues.
About halfway down, the debris from the carving forms a ramp. Now, the carvers can walk up to the facade and continue carving the elaborate capitals and the handsome columns.
TOM PARADISE: We don't know of any other culture or society using this kind of engineering technique for this scale of construction.
NARRATOR: The top-down approach turns out to be a brilliant innovation for carving these tombs in Petra's sandstone cliffs.
But carving is only part of the Treasury's grandeur. Its impressive location commands the head of the canyon and the entrance to the city. Yet the same narrow canyon that creates this dramatic reveal can also be a deathtrap.
These amateur videos capture a rare but deadly desert hazard: flash floods.
Petra's average annual rainfall of just a few inches can hit all at once and pour down this gorge with deadly force. Flash floods took the lives of 22 French tourists here in 1963, and even today, could damage the Treasury.
Ueli Bellwald, a Swiss architect and archaeologist, has come to Petra to protect both tourists and the Treasury. He's searching for clues to how the Nabataeans held back the floods.
UELI BELLWALD: When they decided to carve this facade into the cliff, they had to do something against flash floods in wintertime.
NARRATOR: Next to the Treasury is a narrow gorge. Here, Bellwald finds huge blocks, mortared together to form an ancient dam.
UELI BELLWALD: It's 2,000 years old and still totally preserved.
NARRATOR: But this one dam would not be enough to protect the Treasury, so Bellwald is on the hunt for more dams.
While the landscape appears to be plain rock, to Bellwald it is packed with clues. He notices different colors on the canyon wall. Above this line, the stone is dark. Below it's lighter, which Bellwald believes is caused by mineral deposits from water once stored here in a reservoir.
Following this water line brings him to an area where two deep grooves have been carved into the canyon walls. The grooves show where a dam once stood.
UELI BELLWALD: All of these dams had to be anchored into the cliffs on both sides, that they could easily withstand the pressure of the retained water.
NARRATOR: Following these clues, Bellwald has uncovered an ancient Nabataean dam system.
The Nabataeans built five dams. And to make those dams even more effective, they carved a channel 140 feet long and 16 feet deep to reroute some of the water. This created a large area to store overflow and reduce the force of the water before it reached the Treasury.
It's an engineering feat almost as impressive as the Treasury itself.
UELI BELLWALD: They realized that if they divert the water, they allow the water to spread out to a much bigger surface. And this reduced its speed tremendously.
It worked perfectly.
NARRATOR: So perfectly, Bellwald can't improve on this design. Today, a team is repairing this ancient dam network so it can once again protect the Treasury.
UELI BELLWALD: If we want to keep the Treasury for the future, we have to protect it again, as 2,000 years before, from flash floods. And that's exactly what I'm doing.
NARRATOR: Because the threat of floods was so great, Bellwald believes the Nabataeans must have built the dam system and the Treasury at the same time.
In fact, scholars now believe the grand tombs, the city center, and the water systems, most of the ancient city of Petra, were built within a hundred years, around the birth of Jesus.
UELI BELLWALD: The entire hydraulic infrastructure of Petra was built following one master plan.
NARRATOR: So just how much water did that system provide? Back in San Jose, Charles Ortloff is figuring that out.
CHARLES ORTLOFF: These are the main supplies of water from all of the cisterns, all the dams.
NARRATOR: Ortloff has mapped every water feature he and other archaeologists have discovered: eight springs for fresh drinking water, 36 dams to protect the city from flash floods, over 100 cisterns and reservoirs to collect and hold rainwater, and 125 miles of pipeline to connect many of these features into one integrated water system.
From the map and his flume experiments, Ortloff can estimate the total amount of water available to Petra's 30,000 people.
CHARLES ORTLOFF: If you sum up all of the water from various sources, that would lead to eight liters per person, per day.
NARRATOR: Eight liters is about two gallons. In a world before showers and washing machines, that's more than enough water to survive on.
In fact, new discoveries reveal that the Nabataeans had enough water to transform Petra into a desert oasis. Evidence of that water surplus is being found right next to the Great Temple, in a large open terrace.
It was named by early explorers as the “Marketplace,” so when Leigh-Ann Bedal began digging here in 1998, that's what she expected.
LEIGH-ANN BEDAL: Because it had been called a marketplace, I came in prepared to excavate a market.
NARRATOR: But as she began digging, at eight-feet deep, she discovered waterproof cement.
LEIGH-ANN BEDAL: So we knew that we had something containing water, something deep.
NARRATOR: Her team excavated further and discovered a subterranean structure.
LEIGH-ANN BEDAL: We have the southwest corner here, and directly to the north is the northwest corner.
NARRATOR: Bedal located all four corners to discover overall dimensions of 140 by 80 feet, nearly the size of an Olympic swimming pool.
Then, in the middle, she found evidence of a stone platform, and surrounding the sunken structure, channels, likely used for irrigating a lower terrace, where soil samples suggest the area had been cultivated.
When she puzzles the evidence together, Bedal concludes the marketplace was, in fact, a huge ornamental pool complex, including an island pavilion in its center and a garden on a terrace below.
LEIGH-ANN BEDAL: So if you could imagine, below us, this large pool of water and then a green garden with date palm trees and flowers. This is something that is for showing off.
NARRATOR: Throughout the city center, archaeologists are finding other decorative water features, like fountains and a canal running beside a colonnaded street.
LEIGH-ANN BEDAL: It is really conspicuous consumption of this precious resource, water, in this desert environment.
NARRATOR: Conspicuous consumption of water in the middle of a desert? It seems Petra resembled another flashy desert destination.
LEIGH-ANN BEDAL: A great comparison is Las Vegas, where you have this very arid desert surrounding this oasis city. Where everywhere you go you see the use of water, fountains. By diverting a precious resource into a wealthy center, it sends a message to anybody who sees it that it is a place of wealth and power.
NARRATOR: For ancient visitors, after days of traveling on camel, through the hot parched desert, entering this oasis city must have made a powerful impression. Petra's luxurious pools and internationally-inspired architecture likely sparked the legends that echoed through the ages.
Back in California, after two months of carving, and nearly two thousand years, architecture of far-off lands emerges from the rock.
TOM PARADISE: We've got Assyrian, Egyptian, Greco-Roman, but you put it together, you stand back, and it's Nabataean.
NATHAN HUNT: And now it's a little bit Californian.
NARRATOR: Whether the Nabataeans were carving tombs for the dead, or water channels for the living, their mastery of stone was the key to Petra's wealth and beauty.
So why did the Nabataean kingdom decline and Petra largely disappear? Across the city, collapsed columns point to a prime suspect: ancient texts record a huge earthquake in 363.
SUE ALCOCK: As a result, for a while, when archeologists came to Petra, any time they saw something like this they would say, “Ah, this fell down in 363.”
NARRATOR: But one catastrophic earthquake does not provide the whole picture of the city's decline. At the Great Pool, the most luxurious place in Petra, there's evidence that hard times hit the city even earlier.
LEIGH-ANN BEDAL: It may have been as early as the second century, because at that point, then, we find a lot of animal bones at the bottom of the pool. So, it seems to have been used for trash.
NARRATOR: Found in the great pool, this layer of fallen rocks dates to around the 363 quake. But below that, the layer of soil containing the animal bones indicates the pool filled in at least a hundred years before.
And there is evidence of more destruction a hundred years after the great quake, which may have fatally weakened the city's protective dams. Large sections of Petra's main street are missing pavers. Tom Paradise believes they were washed away in a catastrophic flash flood.
TOM PARADISE: The floodwaters rushed down through Petra's city center, ripping up cobblestones. This flood inundated the city and may have marked the end of Petra's golden age.
NARRATOR: Ironically, the very water that brought life to Petra, may also have contributed to its demise.
Today, in the hills of Southern California, the carving team is bringing a bit of Petra back to life. The final flourish will be a feature not found in other cultures: a Nabataean-style capital, with a simple knob in its center.
NATHAN HUNT: Normally there is a detail here. Typically there is a leaf or a flower here. You never really see it left in this very abstract form. It's quite beautiful in its simplicity.
NARRATOR: Paradise believes the Nabataeans choose this simple form out of respect, almost reverence, for the sandstone.
TOM PARADISE: Their sense of the rock as a living material that had to be, sort of, caressed and worked was really as remarkable as their engineering expertise.
NARRATOR: And the sandstone itself becomes a tool to finish the surface of the tomb.
NATHAN HUNT: I'm using the same stone that we carved off the rock. I'm just rubbing the last little stages, just kind of carefully finishing off that last surface.
NARRATOR: Stone is at the core of Nabataean lives. The very name for their city, “Petra,” comes from the Greek word for rock.
TOM PARADISE: The Nabataean relationship with their sandstone was fundamental to who they were. They're born in this valley of rock. They live in this valley of rock, and then, when they die, they are buried in the rock itself. These hewn tomb facades become their final resting place.
NARRATOR: Each year, over half a million tourists retrace the steps of the explorer Johann Ludwig Burckhardt and gaze up in awe at the Treasury. But in the two centuries since Petra was re-opened to the Western World, its distinctive engineering and culture is proving equal to that of any ancient civilization.
CHRIS TUTTLE: Petra is more than a city. It was the seat of a kingdom, a kingdom whose peace and prosperity was the envy of the ancient world.
NARRATOR: Cisterns, channels, dams, even fountains and pools, the Nabataean mastery of water fueled their astonishing city of stone.
SUE ALCOCK: The water features are underpinning everything. If the Nabataeans couldn't control the water, you wouldn't have a city here.
NARRATOR: Over 2,000 years ago, a desert tribe settled among these forbidding cliffs and transformed this hostile landscape into an oasis.
TOM PARADISE: The Nabataeans learned how to maximize these limited resources to produce a society and a culture that thrived and prospered for hundreds and hundreds of years.
NARRATOR: Burckhardt came here chasing legends of a city lost in the sands of the desert, a city with riches from all over the known world, buildings that rivaled Egypt and Rome, and fountains and pools overflowing with water.
Today, it's clear many of the legendary splendors of the lost city of Petra are true.
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
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