Kildonan Castle is a 14th century stone rectangular tower house, founded by the MacDonalds. Built on a rocky promontory, the three storey tower is defended by steep slopes down to the beach and a northern ravine. In 1406, King Robert III granted Kildonan to John Stewart of Ardgowan and in 1544 it passed to the Hamiltons. The basement and first floor hall once had barrel-vaulted roofs and the crudely mortared walls of this crumbling ruin stand to third floor level. There is now no trace of the turnpike stair or an entrance but the basement with its two gun-loops is still vaulted. 12 miles north is Brodick Castle.