Built in the mid-15th Century by Sir Colin Campbell, 1st Lord of Glenorchy. It started life as a five-storey Tower house with a courtyard defended by an outer wall. A range, hall and some further buildings were added during the 1500s and 1600s.
Not often appreciated today is that when built, Kilchurn was on a small island in Loch Awe scarcely larger than the castle itself: you can see this on a map by Timothy Pont in the late 1500s. Sources suggest it was accessed via an underwater or low lying causeway: looking at the castle today we see that when water levels were lowered by dredging the loch's outflow in 1817, they didn't drop by far.
A significant turn in Kilchurn's history came in 1681. In that year, Sir John Campbell of Glenorchy was made first Earl of Breadalbane. His aim by 1689 was to take advantage of the turbulence when William & Mary become joint sovereigns. To this end he spent much of the 1690s converting Kilchurn Castle into a modern barracks capable of housing 200 troops. This saw the addition of a three storey L-shaped block along the north side of the castle.
The Castle was used as a Government garrison during the 1715 and 1745 Jacobite Rebellions: but the family's efforts to sell it to the Government were unsuccessful. They left in 1740 and moved to Taymouth Castle. In 1760 the castle was badly damaged by lightning and was completely abandoned. Standing as an iconic ruin, it is now in the care of Historic Scotland.