This is a cashel, the Irish term for a ringfort built from dry-stone walling rather than earthen banks. Where the more familiar earthwork ringforts were thrown up from soil and turf, a cashel required the patient gathering and stacking of stone, and the one at Cooleenlemane still retains a wall standing to about 1.1 metres in height and 1.6 metres in width, enclosing a roughly circular space measuring 16 metres north to south and 18 metres east to west.

Ringforts of this kind were the basic unit of rural settlement in early medieval Ireland, typically serving as a defended farmstead for a single family and their livestock. Thousands survive across the country in varying states of preservation, yet each one carries the particular logic of its chosen ground. Whoever selected this spot in Cooleenlemane placed the enclosure at precisely the point where the valley opens up to the south, giving a long sightline down the glacially carved U-shaped valley below. That positioning, combining defensible height with a commanding view, is characteristic of the care early farmers took in reading a landscape before committing stone to ground.