Basilica of San Clemente

Basilica of San Clemente in Italy takes you through nearly two thousand years beneath a medieval church. The twelfth-century basilica presents an apse mosaic, a Cosmatesque pavement and a marble choir screen from an earlier church. Early Renaissance frescoes remain on the walls, alongside the ambons and episcopal seat. Together, these details give the upper church a richly layered interior.

A passage through the sacristy leads down to a fourth-century basilica. Cooler air, narrower spaces and medieval frescoes from the eighth to eleventh centuries mark the descent. Excavations also uncovered a monumental baptistery, a sacristy and a sixth-century marble pavement. Beneath them lie first-century Roman buildings, including a probable house with a courtyard, an underground gallery and a vaulted room.

By the late second century, the vaulted room had become a sanctuary of Mithras. Water still runs through an ancient sewer near the Roman walls, where rising street levels buried earlier foundations. Joseph Mullooly recognised the hidden lower structures in the nineteenth century, and excavations from 1857 to 1870 brought them back to light. At the deepest level, a church, another church and a Mithraic sanctuary remain stacked beneath your feet.