San Silvestro in Capite

The Basilica of Saint Sylvester the First, also known as, is a Roman Catholic minor basilica and titular church in Rome dedicated to Pope Sylvester I. It is located on the Piazza San Silvestro, at the corner of Via del Gambero and the Via della Mercede, and stands adjacent to the central Post Office.

Built in the 8th century as a shrine for the relics of the saints and martyrs from the Catacombs, the church is the national church of Great Britain. The Latin words "in capite" refers to the canonical title of Pope Sylvester the First, to which in capite means in First, in Chief, or in Head. The basilica is also famous for a relic, a fragment of a head purported to be that of John the Baptist, kept in a chapel to the left of the entrance. A second Roman church dedicated to Pope Sylvester I is San Silvestro al Quirinale.

Source: Wikipedia