Porte de Mars is a well preserved third century AD ancient Roman triumphal arch in Reims.

Comprised of three wide arches and still adorned with many friezes portraying ancient legends, including that of Romulus and Remus, Porte de Mars was dedicated to the Roman god of war.

At the time of its construction, Porte de Mars would have been one of four arches which would have led to the Gallo-Roman settlement of Durocortorum, as Reims was then known.