Built in 1727 by Denis O’Conor, who had received a partial return of O’Conor Don lands just seven years earlier, this two-storey house became the home of his son Charles O’Conor, the renowned antiquarian, during the 1750s. The inscription ‘DOC 1727’ above the doorway proudly announces its construction date, though the building itself tells a more complex story. The house incorporates medieval dressed stone, including a now-missing ventilator, suggesting either an earlier structure on this site or materials salvaged from the nearby castle site about 380 metres to the south.

The architectural details reveal a substantial Georgian residence measuring 13 metres east to west and 8.5 metres north to south internally, designed with five bays and a distinctive pediment on its south-facing front. Unusually, the main entrance was positioned at first floor level, whilst two small returns, each measuring roughly 2.7 by 2.45 metres, project from either end of the north wall. The house sits at the northwest corner of what appears to be a walled courtyard or bawn, a 34-metre square enclosure defined by masonry walls up to three metres high and 0.7 metres thick, though this defensive-looking feature likely dates from the Georgian period rather than medieval times.

The site itself holds deeper historical significance, as Bellanagare is believed to be the location of Bealach Coille, recorded in the Annals of the Four Masters in 1489 and possibly the site of a medieval castle. By the early 1830s, the Georgian house had already been abandoned, as noted by traveller Isaac Weld in 1832, leaving behind this intriguing architectural palimpsest that bridges centuries of Irish history. The 1837 Ordnance Survey still identified it as Bellanagare Castle, perpetuating the romantic notion of continuity between the possible medieval fortress and the later Georgian mansion that borrowed its stones and perhaps its spirit.