Faslane Castle, Shandon Castle, and St Michael's Chapel

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. Near the site of Faslane Castle sits the ruinous St Michael's Chapel, which has also been thought to date to the Middle Ages.

Faslane Castle (grid reference NS24949016) is a castle which once stood near Faslane, in Argyll and Bute (and also within the old county of Dunbartonshire). The site of the castle is located about 1.7 miles (3 km) north of the modern town of Shandon; and about 1 mile (2 km) south of the town of Garelochhead. The site sits overlooking the Gare Loch and is today dominated by the Her Majesty's Naval Base Clyde.

In the Middle Ages, the lands of Dunbartonshire were then part of the Lennox, and were controlled by the mormaers of Lennox. The early 13th century mormaer Ailín II granted an extensive tract of land lying on the eastern side of the Gare Loch to one of his younger sons, Amhlaíbh. Descending from Amhlaíbh was Walter of Faslane, who was the great-grandson of Ailín II. On the death of Mormaer Domhnall, Walter became the representative of the male line of the house of Lennox. With his marriage to Margaret, daughter of Domhnall, Walter became mormaer in his own right.

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