The town of Kassiopi, in the northeastern part of Corfu Island, was due to its favorable geographical position the second most important town of the island during the Roman period. The invasion of the Goths in 551 AD caused significant damage to the town, which flourished during the Byzantine period. The castle was erected probably in the between of 12thand 13th centuries. It was built on a rocky hill over the town of Kassiopi and protected both the town and its port, while at the same time it controlled the narrow sea passage between Corfu and the opposite coast.
It has an unequal quadrilateral plan and it was fortified by rectangular and semicircular towers, which were mostly two-storey. The main gate was protected by two rectangular towers. The walls of the castle were mostly constructed by local limestone, in an irregular masonry and the sporadic use of bricks. The castle flourished until 1386, when it was destroyed by the Venetians, after a long siege. The Venetians were not interested in repairing it and they removed building material for the modernization of the Old Fortress of Corfu. Kassiopi was finally abandoned after the Ottoman invasion in 1571.