The structure is a cashel, a type of ringfort built from dry-stone walling rather than an earthen bank, and this one measures roughly 13.6 metres east to west and 13 metres north to south. What makes it worth pausing over is not its scale but its survival: the wall, between one and 1.6 metres wide and still standing up to a metre in height in places, retains intermittent inner and outer facing-stones, with narrow upright flags incorporated into the construction. These details speak to deliberate craft rather than simple enclosure.

The cashel sits within a multiperiod field system, meaning the land around it has been shaped by human activity across several distinct phases, making it difficult to isolate any single period of use for the enclosure itself. It was already being recorded cartographically by 1916, when it appeared hachured on that edition of the Ordnance Survey six-inch map, the hachuring indicating the surveyors recognised the raised or banked character of the feature. Low foundations survive in the south-east quadrant of the interior and may be contemporary with the main wall, possibly the remains of a structure once sheltered within the enclosure. The ridge location, commanding views from south to north-west, follows a pattern common to cashels across the west of Ireland, where siting on elevated ground served both practical and perhaps social purposes. Two further enclosures lie nearby, one approximately 180 metres to the west and another around 160 metres to the east, suggesting this part of Lislarheenmore was once a more densely organised landscape than its present appearance might suggest.