Dedicated in 315, it is the latest of the existing triumphal arches in Rome, from which it differs by spolia, the extensive re-use of parts of earlier buildings.
The arch is 21 m high, 25.7 m wide and 7.4 m deep. It has three archways, the central one being 11.5 m high and 6.5 m wide, the lateral archways 7.4 m by 3.4 m each. The lower part of the monument is built of marble blocks, the top (called attic) is brickwork reveted with marble. A staircase formed in the thickness of the arch is entered from a door at some height from the ground, in the end towards the Palatine Hill.