Dunmanus Castle lies next to Dunmanus Bay, on the north side of the Mizen peninsula in County Cork in Ireland.
Dunmanus Castle was built in 1430 by Donogh More O'Mahony. In 1602 the castle was taken by Crown forces but later recaptured by the O'Mahonys. The castle was still in possession of the O'Mahonys in 1641, and was sold to Emmanuel Moore in 1655, then sold to Sir William Petty. This was all the historical information I was able to find. If you know more, please mail me.
In design Dunmanus Castle seems to be a smaller version of Kilcoe castle. Originally the castle would have been circled by a wall with flankers. The castle now consists of a 4 storeys high rectangular tower. In one corner a 5 storeys high square tower projects on 2 sides Please park by the pier and walk to the cache site as not to block access to the farm next door to the castle.
A very nice castle ruin, freely accessible. Too bad it's not possible to get to the upper floors.