The site, marked on 17th-century Down Survey maps, sits atop what locals call Castle Hill, though its Irish name, Tulach na Fairscena, hints at a much older significance. When antiquarian John O’Donovan visited in the 1830s, he noted that the hill appeared to have been an ancient fort long before any castle was built there, and local tradition held that it was once called Port Righ, meaning “Seat of the King”.

The castle’s turbulent history reads like a chronicle of medieval Irish conflict. The Annals of the Four Masters record that in 1266, Donall O’Hara met his death at English hands whilst attempting to burn Ardnaree. A century later, the O’Dowd clan seized control, with Donall O’Dowd capturing both Ardnaree and nearby Castleconor in 1371, expelling the English garrison and dividing the territory amongst his kinsmen. The castle continued to change hands violently; in 1532 the sons of O’Dowd took it from the Burkes under cover of darkness, only for the Burkes to return the favour the following year, reclaiming their stronghold in another nocturnal raid.

By 1586, Ardnaree had become the setting for a major military confrontation when Scottish mercenaries, who had come to support the Burkes in their rebellion against Sir Richard Bingham, the Provincial President of Connacht, were decisively defeated in what became known as the Battle of Ardnaree. Today, nothing remains of the castle itself; even by O’Donovan’s time, locals reported that the ruins had been almost completely removed along with much of the hill fort. The exact location remains uncertain, though it likely stood on a prominent hill in what is now Carrowcushlan townland, a silent witness to centuries of Irish warfare and political upheaval.