Astypalea Castle is a fortification located in Astypalea. The castle was built on the site of the ancient acropolis by Giovanni Querini and was continuously inhabited until 1943.
The Castle is located on a promontory, at a height of 130 meters above sea level. It has an oval shape with an acute angle, measuring 112 meters by 40 meters, with the major axis in a northwest to southeast direction. The area of the castle is 3,700 square meters. The walls are 9 meters high, while below are steep rocks in places, with a height of 10 meters. The entrance to the castle is through a 2 meter wide gate which has the form of a simple arch. The passage is 13 meters long and 3.5 meters wide and supported by three cross vaults. Above the entrance is a two-story house. From the city there are columns supporting a blind double arch and above is a pediment.