The medieval castle was built in the 12th century. It stands on a small hill 79 m above sea level, from where it dominates the surrounding plain. It combines elements of Romanesque, Gothic, Baroque and Manueline styles, which is a variation of the late Gothic. The castle is included in the list of the Seven Wonders of Portugal, compiled by the Portuguese Ministry of Culture.
As a result of reconstructions taking place over the centuries, the castle is integrated with the entire city, which has retained its medieval features. The fortress is surrounded by well-preserved defensive walls, over 1.5 km long. In some sections, the walls are 13 m high. Additionally, they are reinforced with square defense towers. You can get to the castle through four gates.