The medieval castle of Alvor, which is also called the Fort of Alvor, is considered one of the most significant monuments of military architecture.

The first building on this site – Carthage Fort was built in the 7th century BC Rectangular fortress was built on top of a mountain. The main gate of the fortress were built much later - in the Renaissance and came to the North. The entrance to this gate was guarded by a tower.

In 436 year the Fort was captured by the Carthaginian commander Hannibal, who renamed the Fort to a fortress called Portus Hannibalis. During the pre-Roman colonization Alvor was an important commercial and trading centre due to the fact that had access to the sea. In 736 the settlement was conquered by the Muslims, but continued to play an important trade centre. In 1189, king of Portugal, Sancho I freed Alvor from Muslims, but as a result of military action, the Fort was destroyed. Unfortunately, in 1191 the Moors again occupied the region. In the XIII century Alvor was conquered from the Muslims, and in 1300 the castle was restored by order of the Portuguese king Dinis.

In the era of Christianity Alvor was one of the main towns in the Algarve, and a garrison placed in a small building of the Fort is square in shape, was always in readiness. The functions of the Fort, the building was completed until about the seventeenth century. After the Portuguese war of independence military forces were deployed in larger FORTS along the coast, and the castle was left in ruins. On-site and outside of the steel building is built.

In 1755 the castle was destroyed in the earthquake. Today the fortress has preserved some fragments of walls with battlements and a tower.