The Arch of Constantine was erected in the year 315 in commemoration of the victory of Constantine I the Great in the Battle of Milvian Bridge. It is located between the Colosseum and the Palatine Hill.
Constructed from pieces of previous buildings, the Arch of Constantine is the most modern of the triumphal arches that were built in ancient Rome. It is 21 meters high, 25 meters wide and is made up of three arches.
The Arch of Constantine is one of the best preserved monuments from ancient Rome. Thanks to its excellent location it is one of the most representative and photographed points of the city.
https://www.rome.net/arch-constantine