The castle served as the chief residence of the McSwyne Bannagh sept, with Niall Mar McSwyne, grandson of the first Chief of Bannagh, dying within its walls in 1524. Built on a rocky outcrop surrounded by sea cliffs on three sides, the fortress was naturally defended, requiring only a fosse and walls on its eastern, landward approach. The site included a tower house, bawn walls with gun loops, and various domestic buildings; remnants of these structures still trace the outline of what was once a formidable coastal stronghold.

The castle’s fortunes shifted dramatically during the Plantation of Ulster when it passed to John Murray, later Earl of Annandale. By 1622, contemporary accounts described it as “a ruinous Castle” with partially repaired walls and a newly built gatehouse, occupied by Herbert Maxwell and his family. The site saw military action during the 1641 rebellion when Sir Ralph Gore’s regiment garrisoned it, but following the second Earl of Annandale’s death in 1658, protracted legal disputes over the estate likely led to its abandonment. The ruins suffered further indignity in the 19th century when locals quarried its stones to build St Catherine’s Catholic Church and later the cemetery wall at Killybegs in 1872.

Today, visitors can still trace the castle’s footprint amongst grass covered rubble and partially standing walls. The best preserved section of the bawn wall rises along the northern edge, whilst a substantial southwestern section still features its original gun loop and evidence of a wall walk. A concrete observation post from more recent times sits incongruously at the western end of the promontory, and conservation efforts in 1929 saw some reconstruction of fallen window elements. Though much reduced from its medieval glory, the site remains evocative of the turbulent centuries when Gaelic chiefs, English planters, and military forces contested control of this strategic coastal position.