Monumental structure, originating in Rome, pierced by at least one arched passageway and erected to honour an important person or commemorate a significant event. It usually spanned a street or roadway and was built astride the line of march of a victorious army during its triumphal procession. Most were built during the empire period. The basic form consisted of two piers connected by an arch and crowned by a superstructure, or attic, that served as a base for statues and bore inscriptions. The large central arch could also be flanked by two smaller arches. The Roman triumphal arch had a facade of marble columns, and the archway and sides were adorned with relief sculpture. Among those built since the Renaissance is the Arc de Triomphe in Paris