The Castelo de Serpa is a 13th-century castle in the municipality of Serpa, Portugal. Serpa had probably served as a fortification during the Roman period at the territory. However, the earliest proof of Serpa’s usage as a fortification dates from the 8th century, during the Moorish occupancy. Later the town and its castle were overtaken by the troops of the first Portuguese King Afonso I (1143-1185) during the Christian reconquest of the Iberian Peninsula.
After the conquest, the village fell again into the Moorish hands who renamed it Scheberim. Nevertheless, it was a short period as the forces of King Sancho II recovered the overtaken lands again in 1232. However, the control of the area over the Guadiana River was in dispute between the Castile kings until the end of the 13th century.
Meanwhile, the Portuguese villagers started the reconstruction of the old Muslim fortress in 1295. Moreover, the Order of Avis, founded by King Afonso I, donated one-third of the incomes of the churches of Moura and Serpa. Accordingly, the villagers sided with the Order of Avis during the 1383-85 Portuguese succession crisis. The village served as a base for the Portuguese troops.
The Torre do Relógio in Castelo de Serpa dates from the 15th century, making it one of the oldest clock towers in Portugal.
The conflicts with Spain outburst again during the Spanish Succession War, in which Serpa fell before the Spanish troops in 1580. Nevertheless, Serpa was also the first to hoist the Portuguese banners again during the Restoration of Independence. During the Restoration, Castelo de Serpa benefited from modernization, but it could not escape deterioration over time, as it was abandoned in the second half of the 17th century. The Spanish troops damaged the castle once more during the War of Spanish Succession by blowing it up with the powder magazine (1707). Finally, in 1870, several walls and towers collapsed.
Castelo de Serpa has been classified as a National Monument since 1954. In 1958, the government of Portugal added an aqueduct section to the castle. Further reconstruction and consolidation works continued throughout the 20th century, removing the debris and rebuilding the walls.