Dunluce Castle is a now-ruined medieval castle in Northern Ireland, the seat of Clan McDonnell. It is located on the edge of a basalt outcrop in County Antrim and is accessible via a bridge that connects it to the mainland. The castle is flanked on either side by steep cliffs, which was an important factor for early Christians and Vikings, who were attracted to the site where there had been earlier Irish fortresses. The first castle was built in the 13th century at Dunluce, which was the seat of the Earls of Antrim until they were impoverished by the Battle of the Boyne in 1690. Since then, the castle has deteriorated and parts of it have been used as material for nearby buildings.