Sinkhole Outside of the Pantheon Reveals Ancient Roman Paving Stones

With Rome on lockdown amid the COVID-19 pandemic, few were around to see a sinkhole open up just outside of the Pantheon the afternoon of April 27. Luckily, no one was injured when the pavement collapsed, reported La Stampa’s Luisa Mosello at the time.

Now, the Agenzia Nazionale Stampa Associata (ANSA) reports that the sinkhole has revealed an unexpected treasure hidden below the Piazza della Rotunda’s streets: imperial Roman pavestones. Officials uncovered seven slabs of travertine—a kind of sedimentary rock—that appear to date to between 27 and 25 B.C.

Per ANSA, the stones were probably part of the paving placed when statesman Marcus Agrippa, deputy to Rome’s first emperor, Augustus, oversaw the temple’s initial construction. A fire destroyed Agrippa’s creation in 80 A.D.; thirty years later, a lightning strike razed a second structure built on that same site. Finally, around 125 A.D., Emperor Hadrian erected the domed building seen today, inscribing it with the Latin version of “Marcus Agrippa, son of Lucius, three-time consul, made this,” according to Ancient History Encyclopedia’s Mark Cartwright.

The slabs in question aren’t entirely new discoveries. ANSA reports that local authorities actually unearthed the stones when laying service lines in the 1990s. Rather than excavating the artifacts, officials opted to leave them underground, where they have remained ever since.

More than twenty years after this initial find, the ancient pavement has emerged intact, protected by a layer of fine pozzolan—a material that acts much like cement when exposed to moisture, says Rome special superintendent Daniela Porro in a statement.

“This is further evidence of Rome’s inestimable archaeological riches,” Porro tells ANSA.

The sinkhole—which measures nearly 10 square feet and is more than 8 feet deep—opened up between the popular Piazza della Rotunda’s fountain and the Pantheon. Though tourists typically fill the plaza, the area was largely empty due to COVID-19 travel restrictions, per La Stampa.

Sinkholes have become an increasingly common occurrence in Rome, worrying officials and experts alike, reported Stefania Marignetti for Adnkronos in January. One hundred such chasms opened up in the city in 2019. The year prior, Rome recorded 175 sinkholes. Comparatively, Naples experienced just 20 sinkholes in 2019.

“The most sensitive area is eastern Rome, where materials were quarried in ancient times,” geologist Stefania Nisio, who is working to track Rome’s sinkholes, told Adnkronos, as translated by Live Science’s Laura Geggel. “The main cause of a sinkhole in the city is the presence of an underground cavity.”

Per the Local Italy, another factor contributing to the problem is the soft, sandy soil on which the city was built. Easily eroded by water, this foundation makes the city’s streets more susceptible to sinkholes.

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Nora McGreevy is a former daily correspondent for Smithsonian. She is also a freelance journalist based in Chicago whose work has appeared in Wired, Washingtonian, the Boston Globe, South Bend Tribune, the New York Times and more.