The origins of the Gothic Castle of Portel are closely linked to João Peres de Aboim, a learned nobleman and close advisor to King Afonso III. Construction began in 1262 and continued during the reign of King Dinis.
Typologically, Portel is a fully Gothic castle, featuring a distinctive heptagonal layout, reinforced at the corners by circular towers. The entrance is protected by an imposing quadrangular keep, rising to approximately 25 metres in height. Inside, the keep has two floors above the wall-walk level, both covered with ribbed Gothic vaults. The main gateway to the inner enclosure is framed by a pointed arch. On the southern side of the structure, a second gate — known as the Beja Gate — created a straight internal roadway crossing the castle grounds.