The old cloister is one of the most beautiful and serene in all of Rome. It was built 1208–1235 by the Cosmati and the Vassalletti families who were celebrated Roman marble-craftsmen. In the center of the cloister are four squares of well-tended garden. Around them are four covered walks protected by a low wall or podium.

In the cloister are found architectural fragments from the ancient basilica, and nearly 2000 pieces of tombstones with inscriptions in Greek and Latin that come from the nearby necropolis.