Thought to have been constructed by the Ionians, this small castle on the hill was repaired during the time of Alexander the Great. It was widened and repaired again by Suleyman the Magnificent in 1522, during which time his 200,000 troops attacked and seized the island of Rhodes. The castle opened as a museum in 1991, after restorations that took ten years. It has seven galleries, and has a collection of archaeological, historical, ethnographic and nautical exhibits. The views of the city are wonderful, with a wonderful panorama day and night.