The round fort at the top of a weather beaten hill is a replica built in 1870, although it is not known whether it is faithful to the original construction. The residence of the O'Neill clan, kings of Ulster from the 5C until the 12C, it was destroyed in 1101 by Murtogh O'Brien, King of Munster. A 23 m diameter tunnel has been built through the 4 m thick wall and there is a spectacular view from the top of the ramparts.