Built during the Restoration War period, the Fortim da Areosa aimed to reinforce the defense of the Atlantic coast of Minho, very exposed to attacks by the Spanish Navy, as well as many fortresses built in the coastal area between Vila Praia de Âncora and Esposende in the same age. It was deployed north of the Santiago da Barra Fort, in Viana do Castelo, to reinforce the crossfire with this fortress, located at the mouth of Lima, and also with the Montedor Fort.

Of small dimensions and simple elevations, Fortim da Areosa has a star shaped design of Mannerist taste, formed by four lateral bastions. The structural typology of this fortress shows evident similarities with the forts of Montedor and Cão, whose planimetry at that time constituted an advance in the defense and watch system.

According to Fernandez Nuñez, this group of Minho strongholds was possibly outlined by the same engineer, and his objective to reinforce the line of fire of the existing strongholds is evident (FERNANDÉZ NUÑEZ, Estanislao, 1987).