The rath at Carhoovauler is a roughly circular raised enclosure, about 28 metres north to south and 26 metres east to west, defined by an earthen bank that rises 2.3 metres on its outer face and a fosse, or defensive ditch, running from north-north-east around to the south. That combination of bank and ditch is typical of a rath, the Irish term for a ringfort, a farmstead enclosure of the early medieval period, roughly 500 to 1000 AD. What is not typical is what was found inside.

In the north-west quadrant of the enclosure lay a souterrain, an underground stone-lined passage of the kind commonly associated with Irish ringforts, used variously for storage, refuge, or both. When this particular souterrain was investigated, it was found to contain three ogham stones. Ogham is an early medieval script in which letters are represented by groups of notches and lines cut along the edge of a stone, usually recording a personal name in a formulaic inscription. Finding one ogham stone reused in a souterrain is not unheard of, since the stones were often repurposed as building material long after their original meaning had been forgotten. Finding three in a single underground chamber at one site is considerably more unusual, and points to a local landscape that was, at some earlier point, thick with inscribed monuments. The bank to the south-south-east carries a gap nearly four metres wide, which would have served as the entrance to the enclosure, and the interior along with the bank itself is now planted with conifers.