First recorded in 1192 alongside the nearby Kilbixy castle, this strategic fortification was built by Meiler FitzHenry, possibly replacing an earlier 1170s structure. The castle’s turbulent early years saw it besieged for five weeks in 1207 during a Leinster war, when the sons of Hugh de Lacy forced FitzHenry to abandon the entire cantred from Birr to Kildare. The fortress changed hands multiple times through marriage and inheritance, passing from Walter de Lacy to Geoffrey de Geneville in 1241, then to the Mortimers in 1308, before eventually reverting to the crown under Edward IV in 1461.

The physical remains reveal a formidable defensive structure built on a naturally advantageous ridge. The motte itself is a substantial conical mound, 51 metres in diameter at its base and rising nearly 12 metres high, topped by a flat platform that once held stone buildings. When antiquary John Brownrigg surveyed the site in 1788, he recorded a round keep on the motte’s summit and rectangular buildings within the triangular bailey below. The defences were particularly sophisticated; a deep ditch, 18 metres wide with an external bank, protected the south side, whilst stone piers that once supported a drawbridge still stand up to 4.5 metres high. Intriguingly, Brownrigg also noted ‘caves’ in the bailey, likely the remains of a souterrain suggesting the motte was constructed atop an earlier ringfort.

Despite its initial military importance, by 1422 the castle had fallen into Irish hands and declined in strategic value. The 1656 Down Survey map depicts what may have been a tower house on the site, and as late as 1682, local accounts describe an ‘antient stately structure’ with impressive ruins still visible. Today, though damaged by a disused railway cutting on the east side and a modern farm road through the northwest, the earthworks remain substantial. The motte’s flat top still shows traces of building foundations, including a semi-circular hollow at the west end and rectangular foundations measuring 8.5 by 4.5 metres on the east side, whilst limestone wall foundations, about 1.2 metres wide, mark the bailey’s perimeter.