The fortress occupies a dramatic headland on the western tip of the Algarve, where the land drops away in cliffs on three sides. Prince Henry the Navigator allegedly established a school of navigation here in the early 15th century and sent his sailors out to map the African coast. The current walls date largely from reconstruction after the 1755 earthquake.
Inside the fortress is a simple 16th-century church (Igreja Nossa Senhora da Graça), the giant stone wind compass (Rosa dos Ventos), and a lighthouse. The views from the cliffs are remarkable — on a clear day you can make out the Atlantic swells breaking on the offshore rocks far below. The site gets busy in summer; arrive early or visit in the late afternoon when the light is better anyway. Admission is a few euros.