The Fort of Santa Catarina stands at the western tip of Praia da Rocha, perched on the cliffs above the point where the Arade River meets the Atlantic. It is a compact seventeenth-century military installation built to control the river mouth and complement the Fort of São João do Arade on the opposite bank at Ferragudo.
The interior is not elaborate — low stone walls, a small chapel, a terrace — but the position is exceptional. Standing on the clifftop battery looking out to sea, with the beach stretching away to the east and Ferragudo visible across the water, you understand immediately why the Portuguese built here. Access is free and the fort is open during daylight hours.