Keiss Castle was originally called Raddar, a medieval fortification of which no history survives. In the late 16th or early 17th century George, Earl of Caithness founded a stone Z-plan tower house on the site. The central rectangular tower is of four storeys, with an attic, the basement is vaulted and on two angles are round towers, one being the stair tower, which supports a square caphouse. Standing against the sea cliff, erosion has collapsed the north-east angle of the tower, which contained the entrance. Visit pending. 6 miles south is Castle Sinclair Girnigoe and 12 miles north is Castle of Mey.