The rath at Cartron in County Roscommon is modest in scale, roughly 21 metres in diameter, and much of it has been obscured by vegetation and livestock damage. What survives is a low scarp, rising between 0.2 and 1 metre, that traces an arc from north-north-east around to the south and west, with some facing stones still visible along the south-west to west stretch. Where the scarp meets the natural gradient of the hill to the north and west, the two simply blend together, making the boundary harder to read.

A rath is an earthen ringfort, the most common monument type in the Irish landscape, typically interpreted as a defended farmstead of the early medieval period, roughly the fifth to twelfth centuries. Most were enclosed by an earthen bank and an outer ditch, known as a fosse, but no fosse is visible here, and no clear entrance has been identified either. What does survive inside the perimeter, at the south-west, is a depression measuring roughly 7.5 metres by 3.5 to 4 metres and no more than 0.4 metres deep. This may be the collapsed roof of a souterrain, an underground stone-lined passage or chamber often associated with ringforts, used variously for storage, shelter, or refuge. The proximity of a cashel, a stone-built equivalent of a rath, sitting approximately 180 metres to the north-north-east, suggests this was not an isolated dwelling but part of a broader early medieval settlement in the area.