The honorary triumphal arch, originally a city gate, was erected as a symbol of the victory at Actium. It was paid for by the wife of Lepidus, Salvia Postuma Sergia, sister of the three brothers. Both of their names are carved in the stone along with Lucius Sergius and Gaius Sergius, the honoree's father and uncle respectively. In its original form, statues of the two elders flanked Lepidus on both sides on the top of the arch. On either side of the inscription, a frieze depicts cupids, garlands and bucrania
This small arch with pairs of crenelated Corinthian columns and winged victories in the spandrels, was built on the facade of a gate (Porta Aurea) in the walls, so the part, visible from the town-side, was decorated. The decoration is late hellenistic, with major oriental influences. The low relief on the frieze represents a scene with a war chariot drawn by horses.
This arch has attracted the attention of many artists, even Michelangelo.