The Fortress of Sagres, also known as Castle of Sagres or Fort of Sagres, is a military structure, located near the Sagres freguesia, in the municipality of Vila do Bispo, in the Algarve region of Portugal. The fortress was built in the 15th century by order of Portugal's Infante Henry the Navigator. Heavily damaged in the 1755 Lisbon earthquake, it was rebuilt in the late 18th century albeit with significant remodeling. It underwent major renovations in the 1960s and 1990s and in 2010. Inside, the Church of Nossa Senhora da Graça, also built by Henry the Navigator, stands out. The fortress is of great historical importance because of its connection to the history of Henry the Navigator and Portuguese discoveries. In 2018 it was the most visited monument in the Algarve, probably in the entire region south of the Tagus.

Sagres is a civil parish in the municipality of Vila do Bispo, in the southern Algarve of Portugal. It has 1,894 inhabitants (2021) in an area of 34.37 square kilometres (13.27 sq mi). It is historically connected to the early Portuguese Age of Discovery.