The ringfort at Boherhallagh sits in the foothills of the Ox Mountains, its roughly circular interior spanning around 35 metres across, with the whole structure oriented so that its banks and ditches follow the contours of a natural rise in the ground. A stream runs along the base of that rise to the north-east and east, which would have added a further line of natural defence or drainage. This kind of site, known as a rath, was typically a farmstead of the early medieval period, its earthen bank and fosse (the external ditch) enclosing a household and its associated activity rather than a military garrison.

The engineering here is legible even now, though time has softened much of it. The inner bank, measuring roughly 5.7 metres wide, still stands to a reasonable height on the northern side, though elsewhere it has slumped to a scarp. The fosse survives in different forms depending on where you look: a shallow depression to the north-north-west, and a more pronounced terrace with a clear external scarp to the north-east and south. A remnant outer bank, little more than a low rim of earth and stone, borders the fosse along the southern and south-western arc. The likeliest entrance was at the north-west, where the scarp is broadly slumped across a width of about three metres and aligns with a natural dip in the ground outside. Inside, the ground is level, but slightly elevated to the north-north-east, where a clump of hawthorn and brambles has grown up around what is probably a field clearance cairn, a pile of stones gathered from the interior over generations of agricultural use. What gives the site an added quality of accumulation is the presence of another ringfort roughly 100 metres to the north-east, suggesting this part of the foothills was a settled and organised landscape rather than an isolated holding.