Fortress of Areosa, also referred to as Forte da Areosa, Forte da Vinha and Castelo Velho, but better known as Fortim da Areosa, is located in Rego de Fontes, south of Vinha inlet, in the village and parish of Areosa , in the municipality and district of Viana do Castelo. It is a small defensive stronghold, polygonal in shape, which was intended to defend the coast and was part of the great coastal defensive system. This fort, like the Forte de Paçô, was built between 1690 and 1702 to house a military garrison, its function was to prevent attacks, kidnappings and looting by sea pirates, mainly on Moroccan and Algerian vessels. Although classified as a property of Public Interest, it has been abandoned for about 50 years and is structurally degraded. It has a single door facing east.