Carnasserie Castle is a five-storey towerhouse and hall range, overlooking Kilmartin Glen. It was built as a residence for the first Protestant Bishop of the Isles, Master John Carswell, soon after the Protestant Reformation in the late 16th century. He was responsible for publishing the first book printed in Scottish Gaelic, a translation of the John Knox’s Book of the Common Order.

Many of the building's Renaissance masonry features survive. As a possession of the Earls of Argyll, it was slighted in 1685 by Royalist Forces during the Monmouth Rebellion for their opposition to King James VII (II of England). The castle has remained a ruin ever since and is now under the care of Historic Scotland.