Constantine founded San Paolo to commemorate the martyrdom of St Paul at nearby Tre Fontane. The church has been destroyed, rebuilt and restored several times; most of the present basilica - the largest in Rome after St Peter's - is only 150 years old. The greatest damage to the building occurred in a fire in 1823, but restorers also contributed to the destruction of the older church. Features that have survived include 11th-century doors decorated with biblical scenes; a strange 12th-century Easter candlestick, featuring human-, lion- and goat-headed beasts spewing the vine of life from their mouths; and the elegant 13th-century ciborium above the altar, by Arnolfo di Cambio. In the confessio beneath the altar is the tomb of St Paul, topped by a stone slab pierced with two holes through which devotees stuff bits of cloth to imbue them with the apostle's holiness.
The cloister is a good example of cosmatesque work, its twisted columns inlaid with mosaic and supporting an arcade of sculpted reliefs. In the sacristy are the remnants of a series of papal portraits that once lined the nave. The modern church has carried on this tradition, replacing the originals with mosaic portraits of all the popes from Peter to the present incumbent. There are only eight spaces left; once they are filled, the world, apparently, will end.