The townland takes its name from a curious 17th century moniker, ‘Ballinglagbomile’, meaning ‘the town of the lake of the hornless cow’. In 1641, George Nugent, described as an ‘Irish Papist’, owned 197 acres here, though no castle appears on the Down Survey maps from 1655. The present structure likely incorporates fabric from an earlier fortified house built around 1600, as suggested by a carved coat of arms dated 1614 and a Tudor Gothic chimneystack at the south end.

The castle as it stands today is an amalgam of building phases spanning three centuries. The main seven bay façade dates from the mid 1600s, but underwent significant remodelling around 1740. Later, circa 1790, the building received dramatic Gothic additions including a three bay breakfront with an attic storey, plus a four bay Gothic wing to the north complete with circular turrets at its corners. These modifications, possibly designed by Thomas Wogan Browne who had family connections with then owner Hugh O’Reilly, transformed the structure into the romantic castellated country house we see today, with its raised battlemented parapets concealing pitched slate roofs.

By 1837, the castle served as the seat of Sir J. Nugent and sat within a 300 acre demesne. The building presents an intriguing architectural puzzle; its nine bay rear façade is delightfully irregular thanks to a bell tower and single storey conservatory, whilst tall Georgian timber sash windows pierce the roughcast rendered walls, creating an elegant contrast with the Gothic arched window frames of the towers. The entrance is particularly striking, featuring a projecting dressed limestone string course and that ancient coat of arms set into the centre of the third floor, a tangible link to the castle’s early 17th century origins.