This rectangular three-storey fortified house, built in the distinctive Scottish style, features two turrets at diagonal corners supported by continuous machicolations from the first floor up. The original structure measures approximately 11.3 metres north to south and 8.45 metres east to west, with well-preserved quoins marking its corners. The northwest turret cleverly forms part of a defensive bawn wall that once extended north and east, whilst both turrets contain pistol loops strategically positioned to cover the house’s vulnerable walls.

The castle’s history is closely tied to the Barnwall family, who held the manor of Robertstown for generations. According to the Civil Survey of 1654-6, Margaret Barnwall, an Irish Catholic widow, owned 530 acres here in 1640, including the castle, a church (now in ruins), a mill, a fishing weir and several cabins. Her late husband was likely Gerald Barnwell, recorded as proprietor of over a thousand acres in nearby Moybologe parish. The graveslab of Alexander Barnwall, who died in 1596, can still be seen in Robertstown church, just 250 metres away. The house appears to have remained occupied well into the nineteenth century, as it’s shown with a roof on the 1836 Ordnance Survey map.

The castle underwent significant modifications, probably in the seventeenth century, when a substantial wing was added to the north side. This addition incorporated the western wall of the original bawn and included barrel-vaulted chambers on the ground floor, one featuring an oven under a brick relieving arch. The original entrance, a lintelled doorway protected by a yett (iron gate), sits in the north wall, with a newel staircase immediately inside leading to the upper floors. The first floor contains a large chamber with a central fireplace in the west wall, whilst narrow doorways provide access to the turrets, which feature two-light windows and those defensive pistol loops. Interestingly, some architectural elements appear to have been recycled from the nearby church, including a pointed doorway and a round-headed window in the south gable, suggesting a practical approach to building materials typical of the period.