The Castle of Chora is situated on an escarpment south east of the district of Chora on the island of Kalymnos, at a height of 255 meters above sea level. This castle was the center of activity of the island during Medieval times, housing at its peak more than 1.000 inhabitants. Although building on the site started around the 10th and 11th century AD most of the fortification dates back to the end of the 15th century AD when the Knights of St. John (who ruled the Dodekanese from 1309 AD to 1522 AD) decided to upgrade the existing structure. The Castle continued to house a large part of the population right up until the 18th century when the threat from pirates and conquerors diminished while the ever growing population moved for the most part to the newly built district of Chora.
The walls protect a surface of some 30.500 square meters. The settlement that included mostly small buildings, was densely populated while most of the available space inside the enclosure was put to use. A total of ten churches are present inside the city and in some of them exquisite postbyzantine murals have survived.