Fort of São João da Foz: Porto's fort facing the Atlantic at the mouth of the Douro

Updated on October 18, 2026

The Fort of São João Baptista da Foz, or "Castelo da Foz", has guarded the mouth of the Douro since the late 16th century. Construction began in 1570 and was completed in 1647; its low, thick granite walls, built for artillery, face the Atlantic Ocean. It lost its military role over time, was used as a prison, and now hosts exhibitions. Above all it is a walking destination for visitors who come down to Foz do Douro: you can walk around it along the esplanade, with the sea on one side and the neighbourhood's white houses on the other.

Highlights

The granite walls

The curtain walls and corner turrets are well preserved. Walk along the glacis: the fort is best seen from outside, with waves pounding the foot of the wall in rough weather.

The esplanade and the view

From the foot of the fort, the mouth of the Douro, the pier and the Felgueiras lighthouse come into view at a glance. At sunset the seafront lights up.

The exhibitions

The fort hosts temporary exhibitions, sometimes with free entry: check the city's programme before coming if you want to see the inside.

Practical info

Tips

The outside is open and free at all hours. For the inside, no official hours or price could be confirmed, and access is limited to certain weekends during events such as Open House Porto. Check with the Câmara Municipal do Porto before making the trip. Combine the visit with a walk to the Felgueiras lighthouse and the Pérgola da Foz; see our guide to Foz do Douro. In a westerly wind, spray can splash the seaward path.