Located on a man-made island on Lough Oughter, the castle is accessible only by boat. It was built in the early 13th century by the Anglo-Normans but was soon seized by the O’Reillys who controlled it until the 16th century. The castle and lands were granted to Captain Hugh Culme as part of the Plantation of Ulster but were then seized by Irish rebels during the 1641 rebellion.
Clough Oughter Castle was used as a prison after the victory of Eoghan Roe O’Neill at the Battle of Benburb in 1646. The castle was finally abandoned after it was badly damaged during a siege by Cromwellian forces in 1653. In 1987, an excavation at the site uncovered at least four phases of building.