A later field wall cuts straight across the interior, bisecting the monument entirely, though whoever built it thought to level the wall again once it cleared the cashel's edge. The result is a place that reads as farmland first and early medieval enclosure second, requiring a certain deliberateness of attention before it yields anything at all.

The structure at Carrownagoul is a cashel, the term used for a ringfort built primarily from stone rather than earth, and this one sits on a slight rise with open views to the south and south-west. Its roughly circular interior measures seventeen metres across on its longest axis, defined by a bank of stone and earth around three metres wide. The bank survives best along the north-west to south-south-east arc, standing just over a metre on the outside and somewhat less within; the rest of the perimeter has been buried beneath generations of field-clearance stone, the accumulated debris of farmers picking their land clean. A probable original entrance gap, about two metres wide, remains visible at the south-south-east. The monument was already recorded on the first edition Ordnance Survey six-inch map of 1842, and appeared again, marked with hachures indicating an earthwork, on the later Cassini edition of 1920. Adding further interest to the immediate landscape, a second cashel lies roughly sixty metres to the west-south-west, suggesting this small corner of County Clare once held rather more organised habitation than the overgrown pasture now implies.