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Roman Catacomb Mystery

Who or what killed hundreds of people hidden in a burial chamber nearly 2,000 years ago? Airing February 5, 2014 at 9 pm on PBS Aired February 5, 2014 on PBS

Program Description

Beneath the streets of Rome lies a city of the dead known as the Catacombs—a labyrinth of tunnels, hundreds of miles long, lined with the neatly laid out tombs of the citizens of ancient Rome. Here, in 2002, maintenance workers fixing a broken water main stumbled upon a previously unknown burial chamber like none other in the complex. It was a mass grave of hundreds of bodies spread across six roughly carved caverns, locked away for nearly 2000 years. Who were these people? And can we discover, after all these centuries, what killed them? Could they be Christian martyrs massacred by the Emperor? Or were they felled by a deadly plague? In “Roman Catacomb Mystery,” NOVA’s forensic investigation follows a trail of ancient clues to uncover new secrets of life, death, and disease in the heyday of a mighty empire.

Transcript

Roman Catacomb Mystery

PBS Airdate: February 5, 2014

MICHAEL SCOTT (University of Warwick): In a labyrinth of ancient Roman tombs, a mysterious chamber comes to light: thousands of bodies stacked on top of each other. This is an incredibly unusual discovery. A mass grave from the days of a golden empire sends archaeologists on a hunt for answers.

PHILIPPE BLANCHARD (National Institute for Research in Preventive Archaeology, France/Translation): The body has the appearance of a sort of mummy. That's quite an unusual custom.

MICHAEL SCOTT: What killed so many people so quickly? Could these be the bodies of Christian martyrs? Or victims of a deadly plague? A chance find, a tomb that confounds all expectations, and multiple mass death: Roman Catacomb Mystery, right now on NOVA.

Beneath the streets of modern day Rome, lies a network of interconnected tunnels that stretch for hundreds of miles, a giant underground cemetery. These are Rome's catacombs. They are over one-and-a-half-thousand years old, and they contain many of Rome's ancient dead.

In 2003, deep within this subterranean labyrinth, a bricked-up tomb was discovered, unlike anything seen before in Rome.

PHILIPPE BLANCHARD (Translation): I had never excavated a site with so many bodies; quite unreal.

DOMINIQUE CASTEX (National Center for Scientific Research, France/Translation): The burials here are quite unlike the other burials in the rest of this funeral complex.

MICHAEL SCOTT: Typically, in Roman catacombs, the graves are neat and orderly, with individual bodies carefully placed into niches, but that's not what the archaeologists find here. This was an ancient mass grave, piled high with thousands of skeletons.

This is an incredibly unusual discovery, tombs packed full of bodies, layered on top of one another. You just don't expect to find this sort of burial in a Roman catacomb.

I'm Michael Scott, and as a classical historian, I've studied burials across the Roman world, but I've never seen anything like this. Who were these people? What did they die of? And why are they buried here in this extraordinary manner?

For the last 10 years, an international team have been trying to find out. The archaeological detectives are looking for clues in the layout of the tomb, in personal possessions and in the bones themselves.

PHILIPPE BLANCHARD (Translation): Our aim is to try and understand who they were, so, in some way, bring them back to life.

MICHAEL SCOTT: But with each new clue, that task will become more difficult than they ever imagined.

Rome's catacombs have been explored and excavated for centuries. By and large, their use, their layout, their architecture is fairly well understood. But then, a chance discovery in one of these catacombs opened up a whole new mystery. Behind a nondescript door on the outskirts of Rome lies the catacomb of St. Marcellinus and St Peter.

Here, in the summer of 2003, a burst water main causes the roof in one of the tunnels to collapse. The hundreds of miles of tunnels that make up the Roman catacombs fall under the jurisdiction of the Vatican. Inspector Raffaella Giuliani is sent in to investigate.

RAFFAELLA GIULIANI (Inspector of Catacombs in Rome/Translation): Just above us is the place where the hole opened that started this whole adventure.

MICHAEL SCOTT: The collapsed ceiling revealed a medieval fresco. The painting is believed to show the two fourth century patron saints of the catacomb: Marcellinus, a priest, and Peter, an exorcist. They appear to be standing guard over a burial chamber.

RAFFAELLA GIULIANI (Translation): When we find early medieval frescos in catacombs, they are usually connected to the presence of a martyrs' tomb.

MICHAEL SCOTT: In the centuries before the Roman Emperor converted from paganism to Christianity, Christians were persecuted, sometimes rounded up and massacred in amphitheaters, all over the Roman Empire, like the Coliseum. The religious painting in the catacombs raises expectations for a martyrs' tomb, but nothing could prepare Raffaella for what lies hidden behind the fresco.

RAFFAELLA GIULIANI (Translation): We found these spaces almost entirely full of skeletons, piled on top of each other.

MICHAEL SCOTT: They have uncovered a mass grave. The burial site is located in an area of the Vatican's underground mapping system, labelled X. They come to be known, as the “X Tombs.”

So are the X Tombs the last resting place of hundreds of Christian martyrs? To find out, the Vatican seeks specialist help.

A team of French archaeologists are called in, led by Dominique Castex and Philippe Blanchard. Both are experienced in excavating ancient mass graves.

(Translation): What were your first impressions the first time you came here?

DOMINIQUE CASTEX (Translation): When I entered, I discovered a huge number of bones. There wasn't enough room to move, so we had to squeeze in.

MICHAEL SCOTT: As excavations begin, six more chambers are uncovered, each piled high with bodies. The tombs are arranged on three separate levels, all located around a central hub.

We need to completely forget these modern walls, here, which are actually working as foundations to stop the six meters or so of rocks above our heads from collapsing on us. This is the crucial bit. This is the largest of the burial chambers. And the archaeologists estimate that it's just under a meter, about 80 centimeters left of compressed bodies still to excavate. This is another of the tombs that was originally full of skeletons, the archaeologists have now removed them all. And there is one, two, three more burial chambers behind us. So, when we stand here, we are surrounded by chambers of mass death.

Altogether, the archaeologists estimate the tombs contain the bodies of at least two thousand people.

Picking their way through the bones, a few personal possessions come to light: a pair of earrings, a hairpin and a small black ring. They also unearth a few coins.

The bones themselves reveal more clues.

DOMINIQUE CASTEX (Translation): You can see connected bones in some places.

MICHAEL SCOTT (Translation): Ah oui, un bassin, alors. (Ah yes, a pool, then.)

DOMINIQUE CASTEX (Translation): Here you have a whole vertebral column with the pelvis…

MICHAEL SCOTT: Oh, yes, a pelvis.

DOMINIQUE CASTEX (Translation): …continuing with the femur.

The corpses were brought here and decomposed here. It was not just a case of throwing bones in.

MICHAEL SCOTT: Most of the bodies are in similar positions, with their shoulders compressed, hands resting on the pelvis and their legs stretched out straight, with ankles touching.

The fact the skeletons are still intact and are packed so closely together, with very little soil between the layers of bodies, suggests that large numbers were buried here at the same time.

PHILIPPE BLANCHARD (Translation): They're all relatively well laid out on their stomachs or on their backs. The bodies were carefully laid out, side by side, head to foot and vice versa, to bury the maximum number of people in an extremely restricted space.

MICHAEL SCOTT: This has to have been a mass death moment, what archaeologists call a “crisis event”: multiple people dying within a very short space of time. To find out more, the team makes a detailed study of one of the tombs where all the bodies have been excavated. By digitally restoring the flesh to the bones, a computer program calculates the original volume of the bodies. And the results are completely unexpected, because the bodies don't fit.

PHILIPPE BLANCHARD (Translation): The volume of all the bodies was bigger than the size of the room.

MICHAEL SCOTT: This means that the bodies could not all have been laid out at once. There isn't enough space. Some bodies must have been placed in the tomb after the bodies below had already decomposed. But because the bodies tend to be stacked together so neatly, we think they were placed here in waves, the victims of a series of mass death events.

For centuries, during the age of the Roman republic, with its famous figures like Julius Caesar, and the early Roman Empire, under emperors like Augustus, the Romans buried their dead in cemeteries just outside the city. In fact, the area directly above the X Tombs, now a bustling suburb of Rome, was once a cemetery. Remnants of gravestones, recycled in the catacombs below, reveal that the upper cemetery was the resting place for the Emperor's elite cavalry guard.

But as the population of Rome expanded during the second and third centuries, the space available became increasingly limited, so they started burying people in underground cemeteries.

Rome was built on a soft volcanic rock, called “tufa,” which could be carved out by hand. These sprawling subterranean graveyards, the Roman catacombs, grew rapidly under the city, but they look quite different from the chambers of the X Tombs.

Despite the fact that corridors in a typical catacomb meander every which way, the layout of the dead was actually fairly regularized. You had your individual tombs, called loculi. Burials in most catacombs were neat and orderly, with a special shelf for each individual body. I always refer to them as bunk beds.

There's still the bones of one poor individual left there.

And if you wanted something a bit more special then you could have a cubicula, a bedroom for the entire family to be put to rest in.

As excavations continue, the bones from the X Tombs are removed and kept in a makeshift storeroom for further analysis. So far, the French team has made a detailed study of around 500 bodies. They're starting to build up a picture of who these people were.

From the pelvis bones, they can tell there is a mixture of men and women. The size and stage of development of the femur bones also gives an idea of their age when they died.

DOMINIQUE CASTEX (Translation): We have a right femur that would form a joint here. And the head is fully formed, there is no sign of fusing, so that means it is an adult femur.

MICHAEL SCOTT (Translation): Are most of them adults?

DOMINIQUE CASTEX (Translation): There are a large quantity of bones, which range from teenagers and young adults.

MICHAEL SCOTT: These people certainly didn't die of old age, but are there any signs of trauma? If the bones are those of Christian martyrs, we would expect to find clear marks of violence, but here in the X Tombs, not a scratch.

DOMINIQUE CASTEX (Translation): Out of 500 individuals you would expect to find evidence of blows or injuries on the skeletons, which we do not have.

MICHAEL SCOTT: None of the bones show any signs of trauma that one would expect if someone had been crucified or, indeed, if they died in battle in some sort of massacre. Despite the fresco of saints outside the tomb, there's no evidence that these are Christian martyrs. So who were they? And why were they buried down here like this? The first step is to try to find out when they died.

One way to establish a possible date for the tomb's occupants is to study the handful of personal belongings uncovered amongst the bones. These earrings were made from fine gold. They have a design that became popular in the first century.

This ring is made of the semi-precious stone, jet, which Romans thought held magical powers. Studying its chemical composition, the archaeologists conclude it came all the way from northern England, in the third century.

Then there are the coins, possibly left as payment to enter the afterlife. Their age is much easier to establish. The oldest coin is of the 10th Emperor, Titus, dating from the first century. The wife of Emperor Antonius Pius features on another, as does Emperor Marcus Aurelius, both from the second century. The last coin was of Emperor Gordian. It's a rarer find than the others; he only reigned for three weeks in the third century.

Coins are fantastic, as they really help us narrow down our range, but there are caveats. You carry coins around in your pocket for a long time and they exist in circulation for ages, and the archaeological contexts here, in which these coins were found, are not secure.

To try and get a more accurate date for the bones, the archaeologists use radiocarbon dating. Surprisingly, the different chambers of the X Tombs come back with different results. The bodies from the two larger chambers date from the second and third centuries, but some of the bodies from the smaller tombs date from the first century. These dates suggest the first burials took place before the use of underground catacombs became widespread, and possibly up to 200 years before the corridors surrounding the X Tombs were built.

This is an exciting revelation. The X Tombs could be among the oldest underground tombs found anywhere in Rome. The dating provided by the coins and the bones and the other finds indicate that these people died between the end of the first century A.D. and the early part of the third century A.D. Now, that period of time in Roman history was, by all accounts, a golden age.

Some of Rome's finest imperial buildings were completed between the first and third centuries: the Coliseum, great bath complexes and ever-larger public forums. The people of the X Tombs, whoever they were, were living at the center of a vast and powerful empire.

At its height, the Roman Empire spanned three continents, 2,000,000 square miles. And its territories stretched from North Africa, Egypt, the Middle East, Asia Minor, across Europe and northwest to the borders of Scotland.

At the very heart of it was Rome, Caput Mundi, the capital of the world. Rome was a multicultural city, full of people and products from around the empire and beyond. This was the world's first metropolis, with a population of over a million inhabitants. This cosmopolitan melting pot is where the people of the X Tombs lived and died.

At their lab in Bordeaux, the French team are searching for more clues to the possible identity of these people. Kevin Salesse is analyzing the chemical makeup of the bones and teeth, in a process called “isotopic analysis.” This looks at the various atomic forms, or isotopes, of chemical elements, like oxygen and carbon, found in organic remains.

The minerals in your teeth are set when you are a young child, and they don't change throughout your life, whereas your bones keep remodeling themselves, so that tells us about where you spent the last part of your life. And, by comparing the two, we can find out whether these people were originally from Rome or whether they came from elsewhere and migrated to the city.

The first isotope Kevin is looking at is a rare form of oxygen, called oxygen-18. Nearly all of the oxygen found in our teeth and bones comes from the water we drink, and that comes mainly from rain. The amount of oxygen-18 in rainfall varies from place to place, depending on climate and location, including distance from the ocean. By looking at the oxygen-18 in bones and teeth, Kevin can get an idea of where an individual was born and lived and compare it to the typical native Roman.

KEVIN SALESSE (University of Bordeaux, France/Translation): Here are the results from the teeth, and here you have the results from the bone samples.

MICHAEL SCOTT: The teeth and bones of native Romans typically have levels of oxygen-18 that lie within the red zone, but the teeth and bones from the X Tombs fall outside this zone. This shows that the people of the X Tombs were not born in Rome, and, even as adults, they travelled around.

KEVIN SALESSE (Translation): The bones tell us the last years of their lives, these individuals most likely moved, from one region to another region. So this group is characterized by great mobility.

MICHAEL SCOTT: According to Kevin's research, the oxygen-18 levels indicate that some of the people of the X Tombs may have come from northern Europe, others from across the Mediterranean, northern Africa. And by studying isotopes of nitrogen and carbon, Kevin is even able to explore what sort of foods they might have eaten.

The bones from the X Tombs reveal a diet rich in meat and fish, more than the average Roman, who lived mainly on grains and beans. These people must have been fairly wealthy for their time.

What's coming through very strongly in the archaeological analysis is that the people of the X Tombs were not from Rome. They came to Rome, but where they were from initially, that is a question that the archaeology is still struggling with. There are some indications it may have been from central Europe but also from elsewhere. This does not seem to have been a homogenous population, all from the same place, but they came to Rome, they lived in Rome and died, all together, in Rome.

The French team are starting to build a picture of who these people were and how they lived, but they also want to find out how they died. We know they weren't martyred. We know, from the dating, that bodies were deposited here possibly over a 200-year period. We also know they were carefully packed in, several layers deep, at a time, and that there was a series of separate mass burials.

What the archaeology is showing is fascinating. Piles of bodies were put in these tombs on top of already partly decomposed bodies. So, what we have is waves of mass death. We know it wasn't massacres, so the best hypothesis for what could have caused this has to be disease.

Disease was rampant in the capital, from tuberculosis to typhoid, leprosy to malaria. During the time of the X Tombs, diseases like these are thought to have killed over 30,000 residents each year.

It's really not surprising, when you realize how most Romans lived. The majority of the population lived in the world's first high-rise apartment blocks. They were called insulae, or islands, and there were thousands of them densely packed into the city.

This is the Insula d'Ara Coeli. It dates from the second century and stood at least five floors tall. Down there is the ancient Roman ground level, that's where the floor was, and the first level was shops and inns, and as you go up, you get the private apartments.

But, you know what? You wouldn't want to be in the penthouse here. While the lower floors were rented to wealthy tenants, the upper levels were for the less well off. The apartments were smaller, the number of people in each room increased, and living conditions were just awful.

Aqueducts brought in fresh water, and the city had an impressive drainage system, but the people of Rome still lived in filth. All the trash and garbage were thrown into the streets, and none of these apartments had toilets connected to the drains, so human and animal waste ended up in the street, too.

The people of the X Tombs may have lived during Rome's golden age, but the streets of the capital were more like an open sewer. Disease raged through the city, and there was no escape, even at the famous baths.

The Romans loved their baths. It was a great place to relax, soak, have a massage, scrub down, chat with friends, catch up on the gossip. The people of the X Tombs would have likely gone to the baths. They were part of the social glue that bound all Romans together.

The baths were attended by rich and poor, young and old, healthy and diseased. In fact, we know that Roman doctors actually prescribed a good soak in the baths for all sorts of ailments. If you had everything from boils to rabies, from diarrhea to tuberculosis, you came to the baths.

The sick and the healthy bathed together, because the Romans had no real idea of how disease spread. The baths really were the perfect place to catch a disease. And new strains of disease were constantly being brought into the city by traders, migrants and soldiers. It's easy to imagine how the people of the X Tombs might have succumbed to waves of infection.

To try to find out what disease might have killed them, the French team bring in a world expert in reconstructing ancient D.N.A. Johannes Krause is a professor of paleogenetics. His previous work studied the Black Death, which struck Europe in the 14th century, killing millions.

By extracting D.N.A. from bones from a mass gravesite in central London, he proved that the culprit behind the Black Death was Yersinia pestis, the bacterium that causes bubonic plague.

Here, in the X Tombs, he faces a far greater challenge. The bones are much older. There may be very little D.N.A. left behind from any disease-causing microbes, or pathogens.

JOHANNES KRAUSE (Eberhard Karls University of Tübingen): So, what we want to have is the genetic material of the pathogen itself. So, we're trying to find places in the skeleton that still might have the pathogen D.N.A. preserved, and what we have found is the best containers for genetic information are actually teeth.

MICHAEL SCOTT: How do you pick the particular teeth that you're going to work with?

JOHANNES KRAUSE: We try to identify teeth that are still intact, they don't have a crack or some hole in the surface, and inside those teeth we might have a little bit of dry blood where the pathogen D.N.A. might still be present.

So, we can actually see that the jaw is just sticking out here. You can actually see these teeth are actually being exposed, and as you see the, the, the earth is, it's all a bit wet, so we should have a good, good chance to wiggle out the teeth, without disturbing much of, of the, of the, of the specimen itself. And it's just perfect to get in here.

I will try to actually take them, take them out of the jaw. We should just test how loose they are. Let me see. Here's a bit, yes. I, the last one here is actually quite loose. Yes, yes.

MICHAEL SCOTT: Perfect.

JOHANNES KRAUSE: Look at that.

MICHAEL SCOTT: Wow. You can see how wet that is, as well.

JOHANNES KRAUSE: It's really fresh, so we just put it in the plastic bag.

MICHAEL SCOTT: And that's what? That's a right…that's a molar, is it?

JOHANNES KRAUSE: That's a molar from the left lower jaw.

MICHAEL SCOTT: The teeth are photographed, catalogued and bagged up, ready for transportation back to his lab in Germany.

JOHANNES KRAUSE: Hopefully, we have a little bit of the pathogen D.N.A. which we can also get out of those teeth, and then reconstruct the D.N.A.; we construct the entire genome.

MICHAEL SCOTT: Johannes believes that some of the people here in the X Tombs might have been killed by one of the most virulent epidemics ever to strike the Roman Empire.

This devastating disease was first recorded around the year 165, when the Empire was ruled by two brothers. It was called the Antonine plague because of the family name of the two brothers: Marcus Aurelius Antoninus and Lucius Verus.

Lucius Verus may have succumbed to the disease.

It's uncertain where the Antonine plague came from. There were reports it started in the Middle East, but the disease swept through the Roman army just at the time when the empire was challenged by invasions from the north. It wasn't long before the Antonine plague passed into the civilian population.

The Roman Empire was a vast and integrated trading network, which also contributed to the plague being able to spread so far and so quickly. It was in Italy, it was in parts of central Europe, it was in the east, it was in Egypt. There is even one report it made it into parts of China. And of course, as the saying goes, “all roads lead to Rome.”

When the plague struck the capital, there was panic and public hysteria. Priests were summoned and religious rites performed to purify the city. The people of the X Tombs would have been vulnerable just like everyone else.

According to Roman Consul and writer Dio Cassius, “two thousand people often died in Rome in a single day.”

In his books, the emperors' physician, Galen, describes some of the symptoms of the Antonine plague: a fever; a rash; diarrhea; foul-smelling feces; ulceration of the windpipe; dry, pustular eruptions of the skin.

No one knows for sure what disease was responsible for the Antonine plague. We do know it claimed more lives than any previously recorded epidemic. Across the empire, something like 5,000,000 people were killed, up to a tenth of the entire Roman population.

The plague struck in waves that lasted from A.D. 165 to 180, then again in 189. It's entirely possible that some of the people in the X Tombs, living in Rome at that time, were killed by this disease that shook the empire.

In his lab in Germany, Johannes Krause and his colleague Kirsten Bos are trying to extract D.N.A. from the teeth samples taken from the tombs.

JOHANNES KRAUSE: Now, I drill out the pulp from inside the tooth, which is now powder. That powder now goes into solution, which is an extraction buffer, where the D.N.A. gets released from the bone.

MICHAEL SCOTT: So our answer could be in that tube?

JOHANNES KRAUSE: I hope so, very much.

MICHAEL SCOTT: This process creates a mixture of billions of D.N.A. molecules. But because the samples are very easily contaminated, the cocktail will contain not just D.N.A. from the bones and potential disease microbes, but also D.N.A. from soil microbes that were present in the tomb.

JOHANNES KRAUSE: It's kind of like looking for the needle in a haystack. So, you have billions of molecules that we get out of those teeth, and maybe just a few hundred come from the pathogen. So there is a lot of sorting and then there is a lot of puzzling.

MICHAEL SCOTT: To isolate any fragments of D.N.A. left over from bacteria or viral pathogens, Johannes has adapted a technique known as “D.N.A. hybridization capture.” He calls it fishing.

On this glass slide are 100 short single strands of synthetic pathogen D.N.A. They include the genetic codes of everything from smallpox to measles, typhus to bubonic plague.

The cocktail of D.N.A. from each tooth is then added to the slide. The synthetic strands now act as bait, to hook out any actual pathogen D.N.A. from the solution.

D.N.A. is a double strand of chemicals. Each strand contains a string of four chemical bases, represented by the letters G, A, T and C. The two strands only stick together when the bases match up precisely: C to G and A to T.

JOHANNES KRAUSE: D.N.A. has this double strand, where you have the bases facing each other, and there is always this A facing with the T, and you have the G facing the C.

MICHAEL SCOTT: And this creates the famous double helix.

JOHANNES KRAUSE: Exactly. And, just if the right sequence kind of matches the opposite sequence, those D.N.A. fragments will actually bind and form the double bond. If they don't match, they will not come together. It's like a magnet, basically it only kind of pulls the D.N.A. together if the strands matches, so, only the pathogen D.N.A. will bind here.

MICHAEL SCOTT: But Johannes is pushing this technique to its limits. It's never been used to fish for so many possible causes of ancient disease.

JOHANNES KRAUSE: We have not just looked for a single pathogen, but we have actually looked for hundreds of them, in parallel, because we don't know what has killed those people, and we don't know if it was one or several pathogens that were spreading in that population during that time.

MICHAEL SCOTT: Johannes and his team are just beginning their search. Even if they manage to isolate D.N.A. from a disease-causing bacteria or virus, it could then take months or even years of computer analysis, comparing millions of genetic sequences, to identify which specific pathogen was the cause of death.

This technology, this science, represents the best chance we have of finding out what killed the people of the X Tombs, but for now, the mystery of the deadly disease remains unsolved.

One mystery the archaeologists may be able to crack is the identity of the people themselves. The French team have been doing tests on a white powder that was found in the tombs.

PHILIPPE BLANCHARD (Translation): It was very odd. Right at…from the start we found this whitish material covering the bodies. Our first reaction was to think it was lime. Lime is often used to prevent the bodies from putrefying and from disease spreading. We had some tests done, and when we got the results, it turned out that the material was actually plaster.

MICHAEL SCOTT: It's unusual to find plaster in traditional Roman burials. And this plaster contained further clues about how the bodies were buried.

PHILIPPE BLANCHARD (Translation): We can see particularly well a small imprint, which is, in fact, traces of fabric which have become imprinted on the plaster.

MICHAEL SCOTT: The presence of plaster and fabric suggests these bodies may have been bound in an intricate shroud, which has since disintegrated. This would explain why the shoulders were compressed, hands resting on their pelvis, legs stretched out with ankles touching.

And in among the skeletons and plaster, a second curious substance was discovered.

PHILIPPE BLANCHARD (Translation): In certain chambers, in direct contact with the bones, we uncovered a very large quantity of very fine red flakes, rather like small crystals. In fact, the flakes turned out to be amber, red amber.

MICHAEL SCOTT: Amber was a very expensive material. It was used in burial sites to ensure safe passage to the afterlife. But it's rarely been found in this ground-up form, and never in this quantity. In all, several pounds were recovered from the tombs.

One piece in the puzzle was nearly overlooked altogether.

PHILIPPE BLANCHARD (Translation): I was with Dominique. We were leaning over a skeleton, when I saw this gold thread. I said to Dominique “Have you lost a strand of hair?” She answered, “No. No.”

“Well, in that case, I think we've found a gold thread!” This was at the beginning. The more we dug, the more gold threads we found, sometimes heavily concentrated on the shoulders and collarbones, bands of gold threads, sometimes just small fragments.

MICHAEL SCOTT: Could the people have been buried dressed in gold-embroidered clothes? What began as just a mass of bones is beginning to come into focus a little. We've got a large number of individuals, all carefully laid out, mostly adults, one by the other. And then there are all these strange finds: the white powders, the red powders, the fine gold thread—what they thought to be Dominique's hair.

We're getting a clear picture, now, of an elaborate and expensive burial ritual, for what seem to be some wealthy and distinctive people.

In Bordeaux, more clues are coming to light. One of the French team, Delphine Henri, has been studying remnants of the fabrics that were embedded in the tiny pieces of plaster recovered from the tombs.

DELPHINE HENRI (National Institute for Research in Preventive Archaeology, France/Translation): There are different layers of fabric. You can see, very clearly, we have coarse fabrics, finer fabrics and some very fine fabrics, in certain places.

The very fine, luxury fabrics were made by professional weavers; the coarser fabrics were probably made at home.

MICHAEL SCOTT: Delphine believes she can even work out where the person who made the fabrics came from, by closely examining individual threads in the cloth.

DELPHINE HENRI (Translation): A thread is made by twisting the fibers, and, traditionally, this was done using a spindle. In the northern Mediterranean, the spindle is held at the top, and most people, being right-handed, give it a twist which produces a thread called a Z twist.

MICHAEL SCOTT: Alors, le Z torsion c'est Européen en fait? So, the Z twist is European?

DELPHINE HENRI (Translation): We could refer to it as “mainland Europe.”

And in the southern Mediterranean, they tended to hold the spindle at the bottom and so produced an S-shaped twist.

MICHAEL SCOTT: Delphine found fabrics made both with the Z- and the S-shaped twists. But it's the courser fabrics she finds most intriguing, because they often display the S-twist, in the tradition of the southern Mediterranean. Since these fabrics were probably made at home, it is likely that the people from the X Tombs were either themselves from the south or had slaves from that region.

Philippe believes this cultural connection with the southern Mediterranean can be narrowed further, to North Africa.

PHILIPPE BLANCHARD (Translation): The practice of covering the corpse from head to foot in plaster does lend the body the appearance of a sort of mummy. That's quite an unusual custom. That was really a burial practice that came from northern Africa, probably in the region of Tunisia or Algeria, because we find a lot there.

MICHAEL SCOTT: All this evidence points to these people being outsiders who had travelled around Europe and the Mediterranean and eventually came to Rome. Their diet, their jewelry, the gold threads, all indicate they were relatively wealthy.

So who were they? I think a very important clue may be in the location of the X Tombs. The ground directly above the X Tombs was a site marked out for the burials of a very important group of people.

That's the entrance to our tombs over here. And the big structure behind me, that is the Mausoleum to St. Helena, Emperor Constantine's mum. But ignore it entirely for the moment, because it was built in the early fourth century A.D., way after the time we're interested in. During that time—end-first to mid-third century A.D.—despite what it now looks like—car park, football pitch—this place was actually a really important cemetery for the emperor's personal cavalry.

Now, the name changes over time, but they're perhaps best known as the Equites Singulares Augusti. Equites singulares augusti, is Latin for the “emperors' chosen horsemen,” a regiment founded in the first century A.D.

At the museum of Roman Civilization, we can get a close look at some spectacular reliefs featuring the Equites, as they fought under the command of Emperor Trajan in the second century, battling the Dacians, from what is now Romania.

Here they are, heading off with the Emperor Trajan into battle. These guys really were the chosen ones to share in the emperor's most successful military campaign.

The Equites were the finest Imperial horsemen. Most were foreigners, hand-picked as teenagers from across the empire. They were strong and, by many accounts, very handsome warriors. To be selected was a ticket to great wealth and high status.

This is one of my favorite scenes, the Equites Singulares Augusti in full battle gear—the helmets, the shields, chainmail jackets—on their horses, charging in behind their emperor, Trajan, who offers the horseman's salute, the open right hand. And they are coming to the rescue of the Roman troops that are being besieged over here by the Dacians. It really is the Emperor and his crack cavalry coming to the rescue.

The Equites' official graveyard has vanished, but fragments of tombstones found in these catacombs suggest that the Equites' cemetery was in use above ground at the same time that bodies were being packed into the X Tombs below, which raises an intriguing possibility. It's unlikely a space reserved for elites, as the Equites were, would be used for burials of anyone completely unconnected with them.

RAFFAELLA GIULIANI (Translation): It is possible these chambers might contain dead Equites Singulares Augusti.

MICHAEL SCOTT: The people in the X Tombs were mostly young adults, a mixture of men and women, and we know, from surviving tombstones, that the Equites were often buried with their wives and slaves.

RAFFAELLA GIULIANI (Translation): When they were in Rome, they lived here with their families. This would explain the high number of female bodies that were found in the tombs.

MICHAEL SCOTT: The Equites numbered 5,000 strong. They were foreigners, selected from various occupied territories across central Europe, but also from southern Spain and North Africa. This could explain the distinctive funeral rituals, similar to those in Tunisia and Algeria.

Written accounts also tell us the Equites would dress in jackets embroidered with silver and gold thread.

The Equites were wealthy, well-fed and well-connected. But if many of them died at once, possibly from a raging plague or epidemic, it's conceivable that the Equites community may have converted pre-existing underground chambers, possibly old water cisterns, into a mass burial site.

It's only a theory, and we may never know for sure, but from all the evidence we have, it certainly seems plausible the X Tombs could be the last resting place for over 2,000 of these great horsemen and their families, soldiers especially chosen to protect the Roman emperor.

What I love about this investigation is the way that it has been able to put, not just the flesh back on the bones, but to turn these skeletons back into real people. They came here, to the Caput Mundi, the capital of the world, a kind of ancient Roman version of the American dream. The irony is that it was also here in Rome that disease found its perfect breeding ground and ultimately killed them.

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WRITTEN AND PRESENTED BY
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© 2013 BBC A BBC/NOVA Co-Production

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A NOVA Production by BBC for WGBH/Boston.

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IMAGE

(Relief of Equites Singularis Augusti)
© BBC

Participants

Philippe Blanchard
National Institute of Preventive Archaeology, France
Dominique Castex
Nat Centre for Scientific Research, France
Raffaella Giuliani
Inspector of Catacombs in Rome
Delphine Henri
National Institute of Preventive Archaeology, France
Johannes Krause
Eberhard Karls University,Tübingen
Kevin Salesse
University of Bordeaux, France
Michael Scott
University of Warwick

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