On October 28th, 312, the ancient Ponte Milvio (Milvian Bridge) was the setting for a battle which would change the course of human history.
The Battle of Milvian Bridge was fought between two rival Roman emperors, Constantine I (r. 306-337) and Maxentius (r. 306-312). On the night before the battle Constantine is said to have had a dream, in which he saw the sun (the object of his own worship) and an image of a cross with the message: In hoc signo vinces (In this sign, prevail). The next morning he ordered his soldiers to paint crosses on their shields. In the ensuing battle Maxentius was thrown into the river Tiber, where he drowned. Victory was Constantine's.
It was a victory he quickly shared with Christians throughout the Roman empire when, in 313, the Edict of Milan was passed, giving them the freedom to practise their religion without fear of persecution.
The Pons Milvius was built in 109 BCE by the censor Marcus Aemilius Scaurus to carry the Via Flaminia over the river Tiber. The Ponte Milvio was remodelled by Pope Nicholas V (1447-55), who added the watchtowers. It was restored once again by Pope Pius VII (1800-23), who commissioned the Roman architect Giuseppe Valadier (1762-1839) to erect the triumphal arch at the entrance.