It is an 11th-century Arab castle palace. Remains of its fortified area are still preserved. It is a palace of quadrangular plan with rounded towers except for one of them, known as the Troubadour's Tower, which has a rectangular plan. The rooms are arranged around the courtyard, which is open to the sky. Its roofs, coffered ceilings and plasterwork decoration are some of its greatest charms. It is currently the headquarters of the Aragonese Parliament.