An Chathair Bhearnach, also known as Barnagh Fort, is a caher, the Irish term for a stone-walled ringfort, a type of enclosed settlement built throughout early medieval Ireland, typically between the sixth and tenth centuries. Where earthen ringforts used banks and ditches, cahers relied on drystone construction, and this one still carries enough of its fabric to suggest the effort that once went into it.

The enclosure is roughly oval in plan, measuring about 18.6 metres across its longer axis and 15.2 metres across the shorter. The wall, faced in drystone and now blanketed in sod, survives best along the southern side, where it stands 1.7 metres high on the outside and 2.6 metres wide, though only half a metre above the interior ground surface. To the east it has largely tumbled, leaving low, intermittent lines of collapsed stone pushing through the vegetation. Part of the north-western section has been absorbed into a modern field boundary, a fate common to ancient enclosures in farming landscapes, where a serviceable wall is rarely left to stand idle. Inside the caher, several ill-defined stony mounds have been noted, though whether these represent the footings of former hut structures or simply the accumulation of cleared stone and natural debris has not been established with any certainty.

The site sits on a terrace above a steep fall to the Cummeragh river to the south-east, and from it Lough Currane is visible to the south, that long lake draining toward Waterville on the Iveragh Peninsula. The position, sheltered by the saddle above yet open to the water below, suggests the kind of deliberate, defensible placement typical of early settlement in this part of Kerry, where topography was as useful as any wall.