Basilica of San Clemente

A multi-layered church and archaeological site, the Basilica of San Clemente is one of the best examples of how Rome is a layer cake of history. Entry level is the "new church," a medieval building from circa 1110. Head downstairs to the 4th century basilica that was originally constructed as a patrician home. Follow the sound of running water, and down another staircase to a basement area that was a Mithreaum, a place of worship for followers of Mithras. The water? A natural spring that has flowed since antiquity.