Basilica di San Giovanni in Laterano
Known as the mother of all churches, the Basilica of St. John Lateran is the seat of the bishop of Rome
, a.k.a. the pope. Though slightly less grandiose than St. Peter’s, the Lateran is a masterpiece, known for its massive stacked portico facade designed by Alessandro Galilei. A line of apostles runs the 230-foot length of the church, while a 13th-century mosaic decorates the apse—there’s even a fresco fragment by Giotto. The Lateran’s best-kept secret? The 13th-century side cloister. For a few euro in spare change, the cloister, its unique spiral columns, and the cosmatesque mosaics are all yours.