Santi Quattro Coronati

A fortified monastic complex on the Caelian Hill, between the Colosseum and San Giovanni in Laterano. Founded in the 4th-5th century, dedicated to four early Christian martyrs — likely soldier-stonemasons who refused to carve a pagan idol. The 13th-century Cosmatesque cloister is one of the loveliest in Rome, rivaling those at the Lateran and St. Paul's. Inside, the Aula Gotica (Gothic Hall) was rediscovered with extraordinary 13th-century frescoes in 1995 and is shown only by appointment. Cloistered Augustinian nuns still live in the complex; you ring a bell to access the cloister.