ROME (AP) — The remains of an ancient bridge have emerged in Rome’s Tiber River, near St. Peter’s Basilica, as weeks with virtually no rain caused water levels to plunge.

The bridge — known as Nero’s Bridge, named for the former Roman emperor — once connected Rome’s city center with the Tiber’s right bank.

“Nero is the most famous person linked to this area, because precisely in Nero’s circus, where the Vatican is now located, the Apostle Peter was martyred,” said Antonella Bonini, an archaeologist at Rome’s cultural heritage superintendency.

“However, scholars consider the bridge to be older (than Nero’s era) — built by Caligula, Nero’s uncle,” she said, adding that it existed as early as 39 AD.

The Tiber’s flow has fallen below 80 cubic meters (2,825 cubic feet) per second, about half the historic average for the month of July, according to Giovanni Giganti, coordinator of the Rome civil protection service’s center for water management.

“We are facing a major water crisis. And it is a crisis that is also due to the fact that this winter we did have quite abundant rainfall, but then the dry periods … were quite long,” Giganti said.