Basilica of Saint Clement (Rome)

 basilica, Roman Catholic church

This 12th century basilican church is built on top of a 4th century church, which is of much the same plan. This is in turn built on top of a Roman Mithraeum that belonged to an ancient warrior cult which is considered to be connected with some aspects of early Christianity. At the 1st century level there are also parts of a Roman apartment building. The creek that was drained to form the Roman forum runs under all three layers of the church and can be seen through a grating in the floor outside the Mithraeum. You can visit all these layers of history. The 12th century building gives a good impression of how the early Christian churches looked, including a complete western Atrium or entrance courtyard.