The Fort of São Filipe de Setúbal, also known as Castelo de São Filipe, is located in a dominant position on a hillock, opposite the coastal city of Setúbal, dominating the left bank of the mouth of the Sado River and the Atlantic Ocean, in Portugal.

The project of a modern fortification to defend this stretch of the Portuguese coast dates back to the 14th century, with the construction of the Fort of Santiago do Outão, destined to control the entrance to the river and access to the medieval town. Aiming to expand this defense, in the reign of D. João III (1521-1557), Brás Dias received a regiment in the position of administrator of the works of the Praça and Castelo de Setúbal (July 31, 1526). The financial difficulties, which even led to the abandonment of overseas positions in North Africa (Azamor fort, Arzila fort, Alcácer-Ceguer fort and Safim fort), will have delayed the development of these works .