The Fortim da 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´s a small defensive stronghold, plygonal in shape, wich was designed to defend the coast and was part of the great coastal defensive system. This fort, like the Forte de Paçô was built bettween 1690 and 1702 to house a military garrison, its function was to prevent attacks, kidnappings and ransacking by pirates from the sea, mainly in Moroccan and Algerian boats. Despite being classified as a uilding of Public interest, it has been abandoned for around 50 years and is structurally run down. It has a single doorway facing east.