This Castle built in the 13C houses a military museum. Its crenellated wall, flanked by towers is dominated at an angle by a high keep. A spiral staircase takes you to the first floor whose attractive star-ribbed vaulting rests on Muslim style honeycombed corner squinches. A gallery over the machicolated balcony runs the length of the high wall, just below the top of the castle, which is a remarkable belvedere over the wheat plain of the Alentejo.