The result is a D-shaped enclosure at Dunmaniheen, roughly 20 metres north to south, where the eastern and southern boundaries are not earthworks at all but sheer river precipice, a 24-metre wall of natural rock and soil requiring no human labour. It sits quietly in a private garden between the river and the Killarney to Killorglin road, easily passed without a second glance.

The constructed defences that complete the D are substantial enough on their own terms. An earthen bank running roughly south-west to north-east measures around 3.5 metres wide and rises to about 3.5 metres on the interior face, with an outer fosse, or defensive ditch, roughly 6 metres across running parallel to it. Beyond that fosse, a second outer bank adds another layer of enclosure. The interior slopes steeply downward toward the south, and within it survives a recorded hut site, suggesting this was not merely a refuge but a place where people lived, or at least sheltered for extended periods. Natural springs emerge in the fosse along the south-western arc, which would have provided a reliable water source within or immediately beside the defences. Local tradition holds that a fording point once existed at the south-western corner of the fort, which would make the site's position considerably more legible: placed at a river crossing, commanding both the water route and the approach along the bank, with the river itself doing much of the defensive work on two sides.