Built during the reigns of D. Pedro II and D. João V (1701 to 1740), it has a pentagonal plan and is made up of four bastions connected by their respective curtain walls. Above the entrance door is the coat of arms of D. Diogo de Sousa, the governor in charge of completing the works, and inside there is a small chapel from 1743, dedicated to Nossa Senhora da Conceição. Its construction was intended to defend the interests associated with fishing, an activity that was then the economic support of the town of Póvoa de Varzim.