Alessandra Tarantino / AP

Workers in Rome will have to change the design of a new subway station after discovering military barracks that date back to the second century during the rule of Emperor Hadrian.

The ruins at the Amba Aradam station span 9,700 square feet and lie 30 feet below street level. They once housed the Praetorian Guard, the emperor’s bodyguards, according to archaeologists. The area includes a hallway and 39 rooms, where archeologists have found bronze bracelets, mosaics, and human remains.

Rossella Rea of Italy’s Culture Ministry, in announcing the discovery on Monday, told the Associated Press:

It’s exceptional, not only for its good state of conservation but because it is part of a neighborhood which already included four barracks. And therefore, we can characterize this area as a military neighborhood.

Officials told the BBC that work on the city’s third subway line would not be delayed and is on schedule to open in 2020. Workers will construct around the ruins. The station will be located near an interchange at the Colosseum.

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