The one at Ballynakilla is a cashel, the term used for a ringfort built from stone rather than earth and timber, and what survives has the slightly melancholy quality common to structures that have spent centuries quietly subsiding into the ground.

The cashel measures about 30.7 metres in diameter and would once have been defined by a drystone wall, built without mortar in the tradition common across the west of Ireland during the early medieval period, roughly the fifth to twelfth centuries. That wall has collapsed and grassed over, but where the turf thins or shifts, sections of the inner and outer wall-facing are still intermittently visible, hinting at the original construction. A second ringfort lies approximately 130 metres to the south-west. The pairing is not unusual in the Irish landscape; such enclosures sometimes occur in clusters, possibly reflecting related farming settlements or family groups working adjacent land over generations, though the precise relationship between these two is unknown.

The site sits in open grassland, and because the defining wall has largely collapsed into a low grassed mound, it reads less as a ruin than as a subtle reshaping of the field. Visitors who know what to look for, a gentle circular rise, intermittent traces of coursed stonework at ground level, will find more than those who do not.