Located a short walk west of the Colosseum, this well-preserved monumental arch was erected (sometime soon after 315) to commemorate the victory of Constantine, the first Christian emperor, over his rival Maxentius at the Battle of the Milvian Bridge in 312. In general design, the Arch of Constantine imitates the century-earlier Arch of Septimius Severus (nearby in the Forum) - the quality of its sculptural decoration, however, betrays the slow degradation that Classical Roman sculpture had experienced in the 3rd century AD. Free to view.