The basilica of San Clemente, not far from the Coliseum, is three buildings in one - a church within a church within a church.
The church above ground dates from 1100 and is simply beautiful; one of the most lavishly decorated in Rome. A €3 entrance fee will take you down to the other two levels. There is a fourth-century church below which still houses the remains of ancient frescoes. Below that is the dark and intriguing house of Mitra (the Roman god of the equinoxes), which dates from the first-century, and was later used as a secret meeting place by early Christians. Amazing to think that this labyrinth of tiny rooms and corridors is hidden below two other churches and has still survived.
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