This church (not St. Peter’s) is the cathedral of the diocese of Rome, where the pope comes to celebrate Mass on certain holidays. Built in a.d. 314 by Constantine, it has suffered the vicissitudes of Roman history, forcing many overhauls.

The present building is characterized by an 18th-century facade designed by Alessandro Galilei (statues of Christ and the Apostles ring the top)—a 1993 terrorist bomb caused severe damage to this facade. Borromini gets the credit for the interior, built for Pope Innocent X. In a purportedly misguided attempt to redecorate, frescoes by Giotto were destroyed; remains attributed to Giotto were discovered in 1952 and are now on display against the first inner column on the right.

Across the street is the Santuario della Scala Santa (Palace of the Holy Steps), Piazza San Giovanni in Laterano 14 (tel. 06-7726641). Allegedly, the 28 marble steps (now covered with wood for preservation) were originally at Pontius Pilate’s villa in Jerusalem, and Christ climbed them the day he was brought before Pilate. According to medieval tradition, these steps were brought from Jerusalem to Rome by Constantine’s mother, Helen, in 326, and they’ve been in this location since 1589. Today pilgrims from all over come here to climb the steps on their knees. This is one of the holiest sites in Christendom, although some historians say the stairs might date only from the 4th century.