Ardencaple Castle...

From 1525 Ardencaple Castle was the stronghold of the MacAulay Clan until the death of the last chief in 1786 when the estate and Castle passed out of MacAulay ownership.
It was refurbished by its last owner Henrietta MacAulay Stromberg who died in 1931. The life rent of the Castle went to Adelaide Parker Voorheis until 1935. The Castle was then sold to a consortium of developers who developed the Tower Lawn into a housing estate in 1936-37. This was interrupted by war when the Navy requisitioned the Castle. The Navy finally demolished the Castle in 1957, leaving standing one battle Tower.
This Tower was used as a navigational mark for submarines returning to Faslane until the early 1990's. When the nature and size of submarines changed at that time, replacement navigation towers were necessary in the Firth off Helensburgh. The Tower is still a navigational mark for general shipping on the Clyde.