Crowning a rocky eminence in the centre of town, this 300-year-old castle is built on a classic square plan with four round watchtowers. It was the most important part of the defensive system of Sur, a town that was greatly fortified to protect its illustrious overseas trade. A few traditional artefacts, such as pottery, Quran stands and carpets, help bring some of the rooms to life. You can't miss the castle, as its presence looms over the town centre.