What Roman bridge in Spain over the Tagus River features a central triumphal arch?

The Roman bridge in Spain that crosses the Tagus River and carries a central triumphal arch is the Alcántara Bridge.

Located at Alcántara in Extremadura, the bridge was built between AD 104 and 106 during the reign of Emperor Trajan. It formed part of the road network of Roman Lusitania and was financed collectively by municipalities in the province rather than by a single local community.

The granite structure is about 194 metres long and consists of six semicircular arches. Its central honorific arch commemorates Trajan, while a small temple at one end is associated with the bridge’s architect, Gaius Julius Lacer. The bridge’s height and bold masonry made it one of the most celebrated surviving examples of Roman bridge engineering.

Medieval and early-modern conflicts damaged parts of the bridge, and it underwent repeated repairs. The name Alcántara comes from Arabic al-qanṭarah, meaning “the bridge.” It should not be confused with the Roman bridge of the same name in Toledo.