Lost Temple Swallowed by Ocean Discovered Near Roman Empire's 'Las Vegas'

Marine archaeologists have located a "unique" ancient temple lost beneath the seabed close to the site of what has been dubbed the "Las Vegas" of the Roman Empire.

The temple, thought to date to around 2,000 years ago, is positioned on the opposite side of the Gulf of Pozzuoli to Rome's "Sin City" in southern Italy.

This ancient city, known as Baiae, was the playground of the Roman elite in its heyday. A fashionable coastal resort, Rome's rich and powerful built luxurious villas at the site—including the rulers Julius Caesar, Nero, and Hadrian—attracted by its beautiful setting and healing natural hot springs, not to mention its reputation for hedonistic partying.

Seneca, the famous Roman stoic philosopher, summed up the atmosphere, writing in a letter after visiting Baiae that the city had become a resort of "vice" while bemoaning that it was a "place to be avoided."

"Though it has certain natural advantages, luxury has claimed it for her own exclusive resort... To witness persons wandering drunk along the beach, the riotous reveling of sailing parties, the lakes a-din with choral song, and all the other ways in which luxury, when it is, so to speak, released from the restraints of law not merely sins, but blazons its sins abroad—why must I witness all this?" he wrote.

But Baiae's partying eventually came to end thanks to an unfortunate choice of location. The Gulf of Pozzuoli—which itself forms the western part of the much larger Gulf of Naples—lies in the caldera of a super-volcano known as the Phlegrean Fields, or Campi Flegrei in Italian.

Volcanic activity in this region, such as the movement of magma in subterranean chambers, resulted in the submersion of Baiae over time, as well as other ancient coastal sites dotted along the edge of the Gulf of Pozzuoli.

Baiae has now become a vast underwater archaeological park, with numerous statues, villas and beautifully-preserved Roman mosaics all visible beneath the surface.

While the site of Baiae has been well-documented by scientists, on the other side of the bay to the east, lies the ancient Roman settlement of Puteoli, parts of which are now also submerged beneath the water.

This site has received far less scientific attention to date than its infamous neighbor. But now, researchers are exploring the submerged parts of Puteoli—the site of the modern city of Pozzuoli—in an attempt to reveal new insights into what they say is an area of "extraordinary" archaeological importance. And it was during these explorations that researchers were able to locate the lost temple.

Rome's main commercial harbor

The Romans established Puteoli in 194 B.C. on the site of an ancient Greek colony. There, they took advantage of the natural protection afforded by the bay to construct a commercial harbor.

By the end of the Republican period (509 B.C. to 27 B.C.) and the subsequent reign of the emperor Augustus—who ruled from 27 B.C. until his death in A.D. 14—Puteoli had become the main commercial harbor for Rome, acting as a key hub for the distribution of food and goods from all over the Mediterranean—and beyond—that sustained the city's hundreds of thousands of inhabitants.

While Puteoli is well-documented in literary and historic sources, the submerged structures have only been the subject of relatively limited study, in large part because the area was home to intense industrial activity for most of the 20th century that polluted the water and led to low visibility.

"We have an enormous site underwater with two kilometers [1.2 miles] of coastline submerged and all the structures related to the commercial Roman harbor underwater, but practically everything is unpublished," Michele Stefanile, an underwater archaeologist with the Scuola Superiore Meridionale in Naples, who is coordinating research efforts at Puteoli, told Newsweek.

Since 2021 Stefanile and colleagues have been studying the submerged waterfront of Puteoli, taking advantage of the clearer waters in the bay—a result of the disappearance of most of the modern industries that were located on the coast. Their aim is to create a detailed, high-resolution map of the area and its underwater structures.

To do this, the team have deployed a range of techniques, including using aerial drones to take high-resolution images, exploring the area with remotely operated vehicles and conducting direct underwater surveys. The team have also been utilizing acoustic remote sensing technology that uses sound to map the seabed. This work is beginning to reveal the true extent of what lies beneath the surface of the sea in the Gulf of Pozzuoli.

Lost temple of the Nabateans

One of the most intriguing finds amid the team's research efforts has been the discovery of the site of a lost temple that has been buried below the seabed for centuries in Puteoli's submerged harbor district.

The temple was built by people who came to Puteoli from Western Asia—namely, Nabatean merchants who had set up a commercial base in the harbor area. The Nabateans were an ancient people who inhabited northern Arabia and the southern Levant. They are perhaps best-known today for having built the ancient city of Petra in Jordan, a UNESCO World Heritage Site.

The Nabateans traded incense, spices and other goods, amassing significant wealth and influence, with Petra establishing itself as a major regional hub. A distinct Nabatean kingdom emerged from the mid-3rd century B.C., of which Petra became the capital. But the kingdom became a client state of the Roman Empire in the first century B.C. and in A.D. 106, the territory was annexed, losing its independence.

The first evidence of the presence of the lost Nabatean temple at Puteoli emerged in the 18th century when an altar and two other pieces were found that bore inscriptions dedicated to the Nabatean god Dusares. Subsequently, sport divers found more pieces of the temple—including marble slabs with inscriptions and other altars—between the 1960s and 1980s.

"We don't have the exact location of the first findings, and we know that one of the artifacts was moved from the original position during an attempt at looting, but we are sure that some of the findings came directly from the walls and from the space of the temple," Stefanile said.

Researchers in the 1980s identified a potential area in which the temple might be found. But they were not able to obtain enough support to excavate it and the building's location was almost totally forgotten.

"We completely lost the location—nobody had the exact location," Stefanile said. "We knew it was there but we had to relocate it."

During research efforts this year, armed with a new map of the submerged area they have been developing, Stefanile and colleagues finally managed to uncover the location of the lost temple.

"We started mapping the seabed with aerial drones, and in the months of May and June we started diving on the site, bringing a version of our map with us underwater—it is still not complete, but already useful," he said.

"At this point it was easy for us recognize the structures, and the possible locations of the temple. We arrived to the re-location of the site when we found part of a wall underwater that was very easily recognizable. It is almost completely covered by the seabed, there are just some pieces of the walls emerging."

This temple is "unique," Stefanile said, because it is the only known Nabatean temple in the Roman Empire outside of the Nabatean territories themselves.

The presence of the temple and other evidence at the site helps to paint a picture of a multicultural trade network, with Puteoli acting as a hub for communities of people from all over the Mediterranean world, brought together by their commercial interests.

Aside from the Nabateans, evidence indicates there was a community of people from Egypt—from which Rome imported huge quantities of grain—resident by the harbor, for example. Puteoli was also home to people from western parts of the Mediterranean such as Spain, who were involved in the trade of fish sauces and olive oil.

Merchant communities in Puteoli built their own structures and sacred spaces, as was the case with the Nabateans and their temple, which is thought to have been constructed in the first century A.D. Intriguingly, the temple is constructed in a Roman style with inscriptions written in Latin, although these are dedicated to Dusares.

"This is incredibly interesting because it's evidence of the opening of the Romans to external cults and religions. They allowed merchants to worship their [own] gods," Stefanile said.

As the Roman Republic expanded, it absorbed an ever greater diversity of people, with their own religions and cultures. The Romans were generally tolerant of other religions in this period provided that they allowed for the worship of Roman deities and were not seen to pose a threat to the stability of the state, as was the case with the followers of early Christianity, for example, who were persecuted.

At this stage, the team do not have a reconstruction or 3D models of the Nabatean temple, so its layout and form are not clear, but their plan is to excavate it soon in order to reveal the secrets of the ancient sacred site. Stefanile said the team do not currently know if the temple is simply an "empty box" that is completely spoilt—given that it is so close to the coast—or filled with hidden riches.

Aside from the temple, the team are hoping to excavate other sites of interest in the submerged harbor that they have documented in the course of their work. Their research has revealed a complex series of structures, including storage rooms, shops, and administrative buildings, as well as a huge quantity of marble, columns, pottery, metals and other archaeological materials.

Among the most intriguing finds that the team has documented are dozens of "enormous" granaries below the water that they believe would have once housed food destined for Rome.

"Underwater you have the preservation of all the things you expect to find in a harbor of the Roman time—roads, granaries, docks, quays, embankments, structures for the mooring of ships and also the sacred spaces of the harbor," Stefanile said.

Only time will tell what other riches the underwater archaeologists will find below the sea in the Gulf of Pozzuoli.

Michele Stefanile is featured on an episode about Baiae on the Dive & Dig podcast, hosted by historian Bettany Hughes and maritime archaeologist Lucy Blue, which is available on all major platforms and here.