Dunlough Castle is also known as Three Castle Head, due to its three prominent towers, which are connected by a rampart wall. The naturally well-defended fortification is located in an isolated spot, surrounded by rocky hills on the Mizen Peninsula, with 100 metre cliffs on one side and a lake on the other.

The original tower house was built in 1207, although much of what survives dates from the 15th century. The castle and its walls are constructed from dry stone masonry, without using cement or lime.