Ballingarry Castle, possibly begun around 1280 by the Cantillon family, followed exactly this logic, combining a gateway and curtain walls with a semi-circular bank stretching roughly 120 metres across the mainland approach. What makes this site quietly unusual is that it never remained just a castle. Over several centuries it accumulated a small settlement around it, so that what survives today is less a single monument than the layered footprint of a community that formed, was fought over, and eventually disappeared.

The Cantillons held the site until 1585, when Ballingarry and surrounding lands passed to a George Isham, who appears to have been a largely absent landlord, content to collect head rents while leaving the existing occupants in place. That arrangement did not last. By 1602 a Garrett Roe Stack, brother-in-law to the Lord Kerry, had garrisoned the castle, prompting Sir Charles Wilmot to place it under siege for more than a year. In 1603 a Gerald Mac Morris surrendered and was executed, along with several of the garrison's leaders. A few decades later, during the Cromwellian wars, the site came into the hands of Colonel David Crosbie, a loyalist who substantially remodelled it. According to the eighteenth-century historian Charles Smith, Crosbie built a new small castle, cut two trenches leading to a drawbridge, and constructed a row of houses on the peninsula to accommodate English settler families. His hold on the place was maintained with the assistance of Lord Inchiquin of Clare, who supplied the garrison with food and ammunition.

What the ground now shows is the accumulated result of all this activity. A street of houses runs along the eastern side of the enclosure, their walls levelled to the foundations, all originally built in red sandstone. The 1841 to 1842 Ordnance Survey maps record a sheepfold in the north-east corner, suggesting the site had long since settled into agricultural use by that point. The castle itself, a large rectangular structure measuring roughly 38 metres by 13 metres, sits just north of a low defensive bank at the south-western end. Two small rooms extend from its southern wall, and a square annexe roughly 10 metres across is attached further along. The entrance widths, the room proportions, and the orientation of doorways are all still legible at foundation level, giving the ruins an almost architectural clarity despite their state of collapse.