Kassiopi Castle (Greek: Κάστρο Κασσιώπης) is a castle on the northeastern coast of Corfu overseeing the fishing village of Kassiopi. It was one of three Byzantine-period castles that defended the island before the Venetian era (1386–1797). The castles formed a defensive triangle, with Gardiki guarding the island's south, Kassiopi the northeast and Angelokastro the northwest. Its position at the northeastern coast of Corfu overseeing the Corfu Channel that separates the island from the mainland gave the castle an important vantage point and an elevated strategic significance. Kassiopi Castle is considered one of the most imposing architectural remains in the Ionian Islands, along with Angelokastro, Gardiki Castle and the two Venetian Fortresses of Corfu City, the Citadel and the New Fort. The exact origins of the castle are not clear, with various theories being advanced, but they appear to be Byzantine.[5][6] During excavations in the two towers adjacent to the main gate as well as in a third tower to the north side of the main gate, bronze coins from the reigns of Byzantine emperors Maurice (582–602 AD) and Basil II (976–1025) were discovered. In addition ceramic ostraca dating from the early Byzantine period, the 4th–7th centuries AD, were also unearthed. This leads to the conclusion that a Byzantine castle may have been built in the area by the 6th century AD, a date which is several centuries earlier than the currently estimated date of the present castle's construction.