(Italian: Arco di Costantino) is a triumphal arch in Rome dedicated to the emperor Constantine the Great. The arch was commissioned by the Roman Senate to commemorate Constantine's victory over Maxentius at the Battle of Milvian Bridge in AD 312. Situated between the Colosseum and the Palatine Hill, the arch spans the Via Triumphalis, the route taken by victorious military leaders when they entered the city in a triumphal procession. Dedicated in 315, it is the largest Roman triumphal arch, with overall dimensions of 21 m (69 ft) high, 25.9 m (85 ft) wide and 7.4 m (24 ft) deep. It has three bays, the central one being 11.5 m (38 ft) high and 6.5 m (21 ft) wide and the laterals 7.4 m (24 ft) by 3.4 m (11 ft) each. The arch is constructed of brick-faced concrete covered in marble.
Arch of Constantine
The Arch of Constantine, Rome - painted by Herman van Swanevelt, 17th century
South side, from Via triumphalis. Colosseum to right
North side, from the Colosseum
The Battle of the Milvian Bridge took place between the Roman Emperors Constantine I and Maxentius on 28 October 312 AD. It takes its name from the Milvian Bridge, an important route over the Tiber. Constantine won the battle and started on the path that led him to end the Tetrarchy and become the sole ruler of the Roman Empire. Maxentius drowned in the Tiber during the battle; his body was later taken from the river and decapitated, and his head was paraded through the streets of Rome on the day following the battle before being taken to Africa.
The Battle of the Milvian Bridge (1520–24) by Giulio Romano.
La vision de Constantin by Jacob Punel (ca. 17th century).
A coin struck in 313, depicting Constantine as the companion of a solar deity
The description from 28 October 312, "A cross centered on the Sun", fits with the atmospheric optical phenomenon of sun dog.