Beneath the southern half of an early medieval ringfort, a souterrain, an underground stone-lined tunnel or chamber built by the original inhabitants, runs out of sight below the pasture. These subterranean features are found across Ireland in association with raths, the circular earthen enclosures that served as defended farmsteads during the early medieval period, roughly 500 to 1000 AD. They were used variously for storage, refuge, or ventilation of food supplies. Here, the presence of one adds a further layer of quiet strangeness to a site that is already somewhat difficult to read.

The rath itself is a slightly raised, roughly oval area measuring 34.4 metres east to west and 28 metres north to south, defined not by a bank and ditch in the classic sense but by a scarp, a pronounced change in ground level. That scarp survives in very different condition depending on which side you approach. To the north-east and south-east it has been absorbed into a field fence, topped with post and wire, buried under clearance stones, and largely hidden by blackthorn scrub. On the southern and western arc, however, it retains a stony internal rim, and the base of its outer slope is edged by a close-set kerb of large stones, a detail suggesting some care in the original construction. A straight field wall cuts across the north-western side, while the north-north-east section of the scarp has been incorporated into a wall that, notably, follows the curve of the enclosure rather than overriding it. The interior itself is not uniformly flat; the centre and north-western quadrant sit at a slightly higher level than the rest, separated from the lower ground by a gentle internal scarp curving from north-east to west. A small corrugated iron shed now stands just outside the rath to the north-west.

What makes the broader landscape worth noting is that this site does not stand alone. Another rath lies roughly 150 metres to the north-east, and a third sits approximately 300 metres to the south-east, on the actual summit of a nearby ridge. The Cuillaun rath, by contrast, was placed just below the highest point, a deliberate positioning that appears across many early medieval enclosures, where the precise crest was avoided in favour of a slightly sheltered but still commanding position. Three raths within a few hundred metres of one another suggest a settled, organised early medieval community occupying this part of Mayo, each enclosure perhaps representing a single family's farmstead within a loose cluster of related households.