The Palmela castle is located on one of the highest points in the Serra da Arrábida. It is difficult to get to and was hence ideal for its role in defending the surrounding lands.

During the Christian Reconquest led by the first king of Portugal, Afonso Henriques, Palmela was part of the defensive line built south of the Tagus. At that time, the king bestowed the lands of Palmela, Almada and Alcácer to the Order of Sant´Iago de Espada which took on responsibility for their defence and settlement. In 1205, king Sancho I reaffirmed this gift installing the Order´s Chapter in the castle.

In the 15th century, king João I set about a series of restoration projects, particularly focusing on the donjon tower, and decreeing the construction of the convent that would become the Order´s headquarters as from 1443. The castle underwent further alterations in the 17th century, during the reign of king Pedro II.

The Santiago convent remained active through to the prohibition of religious orders in 1834. After a period left abandoned, the building was restored by the state in 1945 and transformed into thePousada (manor hotel) of Portugal. Entry is free.