Today's church is dedicated to four Roman soldiers, Carpophorus, Severianus, Severius and Victorius who refused to honor a statue of the god Aesculapius and were subsequently put to death. This ninth century church is built over the ancient Titulus Aemilianae, one of the first twenty-five parishes of Rome.

The church was restored under Pope Innocent IV so that it could function as a fortress. It was the only fortified abbey in Rome in the Middle Ages and was used by several popes who did not feel safe in the Lateran Palace.

The church contains the relics of the Four Crowned Saints and also the skull of Saint Sebastian.

Tomorrow we visit San Lorenzo in Damaso.