The cathedral of Rome is San Giovanni in Laterano, not St. Peter's. The church was built here by Emperor Constantine ten years before he built the church dedicated to Peter, and because of its primacy it is the ecclesiastical seat of the Bishop of Rome—also known as the Pope. Constantine obtained the land from the wealthy Laterani family and donated it to the Church. But thanks to vandals, earthquakes, and fires, today's building owes most of its form to 16th- and 17th-century restorations, including an interior designed by Baroque genius Borromini. Before you go inside, look up: at the top of the towering facade, built for Pope Clement X in 1736, 15 colossal statues (the 12 apostles plus Christ, John the Baptist, and the Virgin Mary) stand watch over the suburbs spreading from Porta San Giovanni.
Despite the church's Baroque design, some earlier fragments do remain. Under the portico on the left stands an ancient statue of Constantine, while the central portal's ancient bronze
doors were brought here from the Forum's Curia. Inside, the fragment of a fresco on the first pillar is attributed to the 14th-century Florentine painter Giotto; it depicts Pope Boniface VIII proclaiming the first Holy Year in 1300. The altar's rich Gothic tabernacle—holding what the faithful believe are the heads of Sts. Peter and Paul—dates to 1367. Head to the last chapel at the end of the left aisle to check out the cloister. Encrusted with 12th-century Cosmatesque mosaics by father-and-son team the Vassallettos, it's a break from the Baroque . . . and from the big tour groups that tend to fill the church's interior. Around the corner, meanwhile, stands one of the oldest Christian structures in Rome. Emperor Constantine built the standalone octagonal Baptistery in AD 315. Despite several restorations, a 17th-century interior redecoration, and even a Mafia-related car bombing in 1993, the Baptistery remains much as it would have been in ancient times.