The 1842 edition of the Ordnance Survey six-inch map placed it some 47 metres further to the south-east than it actually stands, a small but telling detail that hints at how easily these low, spread ruins can slip from view.

A cashel is a ringfort built of stone rather than earthen banks, and this near-circular example at Ballyganner measures roughly 27.6 metres north to south and 26.2 metres east to west. Its defining feature today is less a wall than a wide spread of collapsed stone, between five and eight metres across, with the inner wall-face visible only at the west-north-west, where the original construction is still 1.6 metres wide. The outer face, built from large horizontally laid stones, survives intermittently but is best preserved along the arc from north-west to north-east, rising to between half a metre and one and a half metres in height. A rubble-filled entrance, 1.3 metres wide, can be made out on the south-east side. Inside, in the south-west quadrant, there is a souterrain, an underground stone-lined passage typically used in early medieval Ireland for storage or as a place of refuge, as well as a possible trapezoidal structure whose original purpose is unclear. A hollow in the stone spill at the north-east, roughly six and a half metres across, is likely the result of later digging into the fabric of the site. The cashel sits within a large multiperiod field system, suggesting that the landscape around it was organised and worked across several distinct phases of human activity, and a natural east-west ravine runs some 70 metres to the south.