Published: July 2006
In Rome's Basement
Below the city lies the world's largest undiscovered museum.
By Paul Bennett

Luca pushes his head into the sewer, inhales, and grins. "It doesn't smell so bad in the cloaca today," he says, dropping himself feet first into a dark hole in the middle of the Forum of Nerva. Despite his optimism, the blackness emits sickening aroma: a mélange of urine, diesel, mud, and rotting rat carcasses. In short, it smells just as you'd expect a 2,500-year-old continuously used sewer to smell. Below in the dark, tuff-vaulted cavern itself, things aren't much better. As Luca wades through water the color of army fatigues, stepping over garments of temples and discarded travertine washed down over the ages, a diorama of modern life floats past: cigarette butts, plastic bags, plastic lighters, a baby pacifier, and a disturbingly large about of stringy, gray stuff that looks like toilet paper, although raw sewage isn't supposed to be flowing through here. At one turn, Luca points out a broken amphora, perhaps 2,000 years old, lying in the mud next to a broken Peroni beer bottle, perhaps a week old. Together they provide a striking testament to how long people have been throwing their garbage into the gutter of this city.

Luca Antognoli, 49, works for Roma Sotterranea, a group of urban speleologists commissioned by the city to explore Rome's subterranean spaces—an amazing array of temples, roads, houses, and aqueducts buried by history since the fall of the Roman Empire. According to tradition, the Cloaca Maxima ("great drain"), which runs beneath the Roman Forum, was built in the sixth century b.c., making it one of the city's oldest—if not the oldest—surviving structures. So it is surprising to learn, as Luca winds his way through the sludge-filled passage under Via Cavour, that the cloaca has never been fully explored and mapped.

In real life Luca Antognoli is a surgeon, and he has warned us to be careful not to expose our skin to the water, a potent mix of street runoff and raw sewage. Earnest and wide-eyed, he has taken the danger seriously, covering every inch of his body with gloves, boots, hooded wind suit, and mask—all hermetically sealed with duct tape. He motions sharply at a conduit disgorging a surge of ocher liquid into the cavern that aerosolizes into a mist, sending members of the group into a frenzy fitting masks over their faces.

He points out other conduits, some dumping clean water into the sewer from underground springs, some releasing dirty water. At one point, we pass through a sloping section down which brown sludge purls. Beyond this dangerous obstacle lies a deep hole where, sometime during the past 2,000 years, the floor has washed out, forcing everyone to inch along an unseen precipice in chest-high, scum-covered water. A joker in the group observes that it looks like schiuma, the cocoa-like foam on Italian espresso.

At a pile of rubble—bones, pottery sherds, and caked mud that nearly fill the entire space of the cloaca—the adventure comes to a halt. The sewer's barrel vault clearly reaches into the darkness beyond—one wonders how far.

Roma Sotterranea plans to send a remote-controlled robot to probe beyond the barrier; Luca expects to confirm that the great drain reaches the Baths of Diocletian, nearly a mile (1.6 kilometers) northeast. Who knows what treasures lie along the way, he says, noting that archaeologists had recently pulled a colossal head of Emperor Constantine from a sewer just like this, prompting speculation that the first Christian emperor may have been the victim of damnatio memoriae, as the practice of obliterating the memory of despised emperors was known in ancient Rome.

For Luca Antognoli, subterranean spaces like the Cloaca Maxima offer clues about how this city grew to rule an empire from the edge of Scotland to Baghdad, leaving its imprint indelibly on Western history.

A rivulet coming from the darkness flows down the rubble. Someone asks if it's dirty or clean. "It's very dirty," Luca says, eyeing the opening beyond, "but very important."

The cloaca, originally an open drain, was intentionally buried during the time of the Roman Republic, but most of what underlies Rome is there accidentally, buried by two millennia of sedimentation and urban growth.

"Rome has been rising for 3,000 years," says Darius Arya, an archaeologist and director of the American Institute for Roman Culture. Much of Rome is situated in a floodplain, including the modern city center, known in antiquity as Campus Martius, at a bend of the Tiber River. Although the Romans put up levees, the city still flooded periodically, so they built upward, laying new structures and streets on earlier ones. "It was cost-effective, and it worked," Arya says. "We see the Romans jacking their city up two meters [6.5 feet] at a time, raising themselves above the water but also burying their past."

Today the city sits on layers of history 45 feet (14 meters) deep in places. But ironically, while the beguiling truth of Rome is that you can dig a hole anywhere within the 12-mile (19-kilometer) ring of walls that once enclosed the ancient city and find something of interest, comparatively little of this buried city has been excavated.

"I don't imagine more than 10 percent has been documented," Robert Coates-Stevens says. An archaeology fellow with the British School at Rome, Coates-Stevens has been trying for a decade to piece together the topography of ancient Rome. During the 1800s, the Roman Forum was dug out—work that continues—but most ancient structures are still trapped under the traffic-clogged streets and office buildings of the contemporary city. "It's a heady feeling," Coates-Stevens says, "to think that all this still lies beneath our feet awaiting discovery."

In the 1920s and '30s, seized with this kind of excitement, Benito Mussolini razed sections of Rome's historic center, where medieval and Renaissance houses stood, to reveal the layers below—specifically anything dating back to the time of Emperor Augustus. (Mussolini liked to compare himself to Augustus and equated fascism with Pax Romana, the time of peace ushered in by Augustus.) By the 1980s this big-hole approach to archaeology had fallen out of favor, in part because of the financial challenge of protecting the ruins Mussolini had exposed from acid rain, smog, and vandalism. But curiosity about Rome is eternal, and so the vanguard of archaeology has shifted: Archaeologists, and the speleologists they employ, are exploring ancient spaces from below, leaving the surface undisturbed.

Cristiano Ranieri pulls a dry suit over his head and fixes a full-face respirator in place. Above, the hum of tourist traffic bounces off the travertine and brick surfaces of the Colosseum. But down here, among the maze of passages where gladiators would have waited and lifts would have raised lions, bears, and other exotic animals up to the action, the sound is muffled. Ranieri becomes visibly excited as he describes scuba diving beneath the Colosseum, explaining that this space, inside the 40-foot (12-meter) deep "doughnut" foundation that holds up the rest of the structure, isn't even the bottom. He removes a steel plate from the floor to reveal a still body of dark gray water several yards below: the underbelly of the underbelly of the Colosseum.

Ranieri is scouting a new access point into the drain system for a future measuring project. In particular, he wants to know whether he will be able to carry a full underwater lighting rig into this hole or be forced to use portable flashlights. A well-lit swim below the Colosseum could change history.

Until three years ago only a quarter of the conduits—the driest and most easily accessible—below the Colosseum had been explored. These simple drains, designed to whisk away storm water, date from the late first century a.d., when the Flavian emperors were building the Colosseum. Some ancient writers claimed the building was deliberately flooded for mock naval battles. But there was no evidence of the large waterworks needed to bring in the water.

Then, in October 2003, Ranieri, an archaeologist and speleologist with the superintendency of archaeology, made a startling discovery. Below the simple drains (and predating the Colosseum) were large conduits constructed by Emperor Nero to charge an artificial lake in his gardens. The conduits had obviously been reused by the architects of the Colosseum, most likely to pipe quantities of water in and out. For the first few years of its history, at least, the Colosseum, like many other theaters, was capable of being flooded.

Far more common than planned expeditions to reveal Rome's hidden secrets are the chance discoveries: A work crew digs a hole in the street and cracks into a hollow underground space. Speleologists are called in, and yet another astounding find alters the picture. Such was the case on the Oppian Hill two winters ago when, after a period of intense rain, a hole spontaneously opened near a tree, exposing a matrix of underground rooms.

Marco Placidi, a coolheaded speleologist and a founder of Roma Sotterranea, was called in. Using ropes and harnesses, Placidi lowered himself into a dark, 40-foot (12-meter) high room, which archaeologists believe was built sometime after Nero's nearby Domus Aurea ("golden house"), dating from a.d. 65, and sometime before the Baths of Trajan (circa a.d. 109), located above both of these structures. This room, it turned out, is one of the best preserved features from the Roman world, with meticulously flat brickwork and large arches. But for Placidi, the heart-thumping moment came halfway down, when, hanging in midair, he aimed his headlamp at the wall: On it was a mosaic, in perfect condition, showing a group of naked men harvesting and stamping grapes. The "Vendemmia" ("Grape Harvest"), as it was called, is some ten feet long and made of minuscule, vividly colored bits of marble and other stone. "When I dropped down into this hole, I never imagined I'd see something like this," Placidi says. "It was an immense joy."

To an outsider, the randomness of such discoveries is shocking. But for Romans, it is quotidian. In the course of going about his business, someone somewhere bumps up against an artifact that hasn't seen the light of day for hundreds—or thousands—of years. Every year, the city authorizes 13,000 requests for building permits, each of which requires archaeological evaluation. Construction of roads and sewers in Rome's ever expanding suburbs is years behind because the overwhelming number of finds stops work and throws budgets into disarray.

The city of Rome has been trying hard to extend a sewer to the Appian area in the southeast for the past three years but has made little progress, according to Davide Mancini and Sergio Fontana. They run a cooperative of archaeology graduate students called Parsifal, contracted by the city's cash-strapped archaeology office to monitor the work of dozens of construction crews. At any time, Parsifal may be overseeing up to 20 worksites, looking out for artifacts, reporting back to the government, and, if necessary, halting work to analyze finds. Traditional archaeology is painstakingly slow, but Parsifal's experts must be able to spot a precious object and assess its value in the seconds before the shovel plunges in.

On a typical day at the site, as Mancini and Fontana watch, a backhoe has to stop four times in a single half hour. A harried graduate student jumps into the muddy pit and tosses up treasure: a lamp, several plates and bowls, small terra-cotta sculptures, and countless fragments of amphorae—much of which might date from the third or fourth century b.c.

"This zone is a mess," Davide says. He explains that work began here in June 2003, expecting the project would take a few months. But completion is still nowhere in sight.

A few minutes later, the backhoe stops again. The student hops into the hole and sends up several very large pieces of amphorae, one of which has a glob of something stuck to it. Brightening, Sergio sniffs it. He says that it might be resin used to seal the amphora, a rare find. Davide disagrees. He thinks it might be incense, maybe from the amphora's reuse in medieval times. Regardless, the fragment goes into a plastic bag, which goes into a box next to dozens of other boxes that wait for the truck to take them to a warehouse. Meanwhile, the backhoe driver finishes his cigarette and asks permission to continue digging.

Interruptions such as these cannot be planned for in advance, in part because it is impossible to know what the underground has in store. (Ground-penetrating radar, which works well in rural settings, has difficulty differentiating complex, debris-filled soils in continuously inhabited places.) Beyond that, the length of any delay depends very much on the value assigned to what is found. Some things, like amphorae sherds, can be quickly dismissed. Others, like buildings, may need to be sketched, measured, and otherwise documented. And occasionally, if something is unique, the Italian state may mandate that it be made accessible to the public.

This troubles many Romans. "No one wants the Beni Culturali knocking on their door," Robert Coates-Stevens says, referring to the state ministry that oversees archaeology. Traditionally, private property owners have been loath to report that errant column in the basement. But this could change as people come to think of having a piece of ancient history as an asset rather than a liability.

"The marbles were an emotional find," Fendi says. "They are beautiful, and I knew immediately that, if possible, I wanted to use them in our gallery."

Five years ago Alda Fendi, scion of the Fendi fashion empire, bought a section of a Renaissance palace in central Rome just yards from the Column of Trajan. Her interior designer gutted the space for an art gallery, but in the course of the work, laborers digging in the basement discovered architectural footings of the Basilica Ulpia, a law court built by Emperor Trajan in a.d. 112 and attached to his forum. After a brief excavation and documentation, the state archaeologists recommended that part of the paving be restored and left visible. Fendi understood the importance of the find and envisioned incorporating the basilica into her gallery. She got permission to finance continued digging through the foundation of the palace and out under the piazza in front. The work eventually revealed a large section of the Basilica Ulpia, including several columns along with well-preserved flooring made of green and yellow marble and purple Phrygian marble.

Urban speleologists like to joke about their work, poking fun at each other as they slog through sewers scaring each other with tales of rats the size of dogs and other nonsense. But as Marco Placidi and Adriano Morabito slip into their dry suits and descend the spiral staircase called La Chiocciola ("snail shell") in central Rome, they get very quiet and very serious. To them, this is sacred space. At the bottom, the steps drop off into the Aqua Virgo, an underground aqueduct carved through solid rock by Emperor Augustus' right-hand man, Marcus Agrippa, in 19 b.c. It travels more than ten miles from a spring in Salone, source of the most constant pure water supply Romans have ever enjoyed. The aqueduct is still in use, feeding the Trevi Fountain and Gian Lorenzo Bernini's Fountain of the Four Rivers in Piazza Navona.

Roma Sotterranea surveyed the Aqua Virgo for the city's water utility several years ago, fixing its position with lasers, compasses, and the occasional pop to the surface for a GPS reality check. This day the group has returned to double-check earlier work and to float in dry suits through the conduit.

The water, at cheek level, comes directly from the spring and is pretty cold. The walls of the Aqua Virgo, though cut from solid stone, are remarkably regular, recalling the rectilinear blocks of the Cloaca Maxima. But the two spaces couldn't be more different. One brings pure, life-giving water, while the other takes away putrid effluent. If the key to ancient Rome is water, then these two systems form the anchors of a critical continuum.

As the group presses on toward the Trevi Fountain, Nick De Pace, a teacher of architecture at the Rhode Island School of Design on a Fulbright fellowship studying Rome's underground structures, points out the curved lines where excavators scratched their way through the solid tuff 2,000 years ago. He describes a work crew using hand tools to chisel, by torchlight, a smooth, sloping conduit that looks, to modern eyes, as if it had been made by machine. For him, Rome's aqueducts and sewers are emblematic of the can-do spirit of Roman civilization. "Nobody thinks the sewers are that important," he says, examining a stalactite where calcium-rich groundwater is seeping into the aqueduct. "But for me they explain how and why Rome existed."

The exploring party comes to a wall of modern concrete where the original conduit has been truncated and its water diverted into a modern pipe. The pipe takes the flow downhill to the Trevi Fountain and beyond. What might it lead to? A new branch veering off to feed some buried ancient building whose discovery would bring the infrastructure of Rome into sharper focus?

"Rome is the biggest open-air museum in the world," says Darius Arya of the American Institute for Roman Culture." There's so much to explore. I find it funny that people talk about diving to the bottom of the sea or climbing faraway peaks. Here's Rome, where we still don't know what's underneath."