From the surface, it looks like little more than a low, lumpen bank, with a few stones breaking through here and there like knuckles through a glove. Only where turf cutters have worked right up to the structure do the actual bones of the thing become visible: a drystone outer face and a rubble core, built with enough care and mass to suggest this was once a deliberate and substantial boundary.

The enclosure is oval in plan, measuring roughly 10.8 metres northeast to southwest and 12.6 metres northwest to southeast on the interior. Its walls, where probing has been able to establish their extent, are approximately 2.75 metres thick, and they still survive to a maximum height of just under a metre despite being buried under around 0.8 metres of accumulated peat. A gap on the east-southeast side, about 1.8 metres wide, is tentatively identified as the original entrance. Stone enclosures of this kind, essentially circular or oval walled compounds, were a common feature of early medieval Irish settlement, often used to define a farmstead or provide a defended boundary around a homestead. Whether that is the full story here is harder to say. The entrance appears to be slightly out-turned, which in other enclosures can indicate a deliberate funnelling design, though at An Choill Mhór that impression may simply be the result of collapse or uneven peat cutting over the years. The structure was documented by J. Cuppage in the 1986 Corca Dhuibhne archaeological survey of the Dingle Peninsula, a landmark regional survey that recorded hundreds of sites across this exceptionally monument-dense landscape.

What makes this particular enclosure quietly compelling is the way the bog has preserved and concealed it simultaneously. The peat that obscures it from view is also the reason it survives at all, protecting the lower courses of the wall from disturbance and decay. At the few points where the turf has been cut away to its very edge, only about 15 centimetres of peat still separates the old ground surface from the open air, offering a narrow, accidental window into the structure beneath.