A fortified maritime fortress with an irregular star shape, including a convent of Franciscan origin from the 14th century, erected by King João I of Portugal, which was enlarged in 1676.
The barracks and the convent surround the central parade square, the convent being an austere structure with a single nave church with vaulted ceilings, a sacristy and a cloister. The wings of the cloister are composed of Ionic colonnades. The existing well is one of only three in the world that is located at sea and provides drinking water.
Located in Ínsua of Santo Isidro, in Moledo, near Minho river.