Battistero lateranense

The external frieze of 1657, with the Chigi arms, is by Francesco Borromini. The old portico was converted in 1054 into the chapels of Rufina and Seconda and of Cipriano and Giustina, the second of which keeps a fifth-century mosaic.

High on the walls are modern copies of works by Andrea Sacchi showing scenes from the life of John the Baptist; below them, frescoes of scenes from the life of Constantine by Andrea Camassei, Giacinto Gimignani and Carlo Maratta. At the centre of a sixteenth-century circular enclosure stands the font, an urn of green basalt with a bronze cover by Ciro Ferri (1634–1689). Two bronze deer were placed there in 1967 by Pope Paul VI.