Fodor's Expert Review Arco di Costantino
This majestic arch was erected in AD 315 to commemorate Constantine's victory over Maxentius at the Milvian Bridge. It was just before this battle, in AD 312, that Constantine—the emperor who converted Rome to Christianity—legendarily had a vision of a cross and heard the words, "In this sign thou shalt conquer." Many of the rich marble decorations for the arch were scavenged from earlier monuments, both saving money and placing Constantine in line with the great emperors of the past. It is easy to picture ranks of Roman centurions marching under the great barrel vault.