Faslane Castle and Shandon Castle were two mediaeval Scottish castles which once stood between the towns Garelochhead and Helensburgh, near the shores of the Gare Loch, in Argyll and Bute. In the 19th century, the castles were thought to have dated back to the Middle Ages. At that time period, they were situated in within the mormaerdom of Lennox, which was controlled by the mormaers of Lennox. Today nothing remains of Faslane Castle; though in the 19th century certain ruins of Shandon Castle were said to have still existed.