Kildonan Dun is a remarkably well preserved dun, or fortified farmstead It can be found 50 yards or so east of the B842 at a point about mid way between Campbeltown and Carradale. There is a Forestry Commission car park on the opposite side of the road a short distance north of it. You can access it via a wooden stile from the road and along a grassy path that leads between bracken that can be taller than you are.
The Dun is a roughly D-shaped enclosure surrounded by stone walls that rise to around a metre internally, and about twice that externally. Depending on when you visit you may have work your way through the bracken and vegetation.