Basilica of San Giovanni in Laterano

This guide to the Basilica of San Giovanni in Laterano in Rome makes the case that this, not St. Peter's, is the Pope's true cathedral, tracing the title back seventeen centuries to Emperor Constantine's victory at the Milvian Bridge in 312 and his donation of the Lateran family's estate soon after. It follows Pope Sylvester's fourth-century dedication and the two medieval fires that drove the papacy into exile in Avignon. Take a moment at the Gothic baldachin above the main altar before the guide tells you what has been kept inside it since the ninth century.