The structure is a rath, the Irish term for a ringfort, the most common monument type surviving in the Irish countryside. Ringforts are roughly circular enclosures built during the early medieval period, typically between the fifth and twelfth centuries, and were used as defended farmsteads by a single family or small community. Most were defined by one or more earthen banks thrown up from an internal ditch, and this one in Ballyphilibeen fits that pattern closely, its bank still clearly legible in the landscape despite centuries of agricultural use.

The earthwork measures approximately 29 metres across on its north to south axis, a modest but solid presence on a south-facing slope. The enclosing bank stands about 1.5 metres above the interior ground level, and rises to 2.1 metres when measured from the outside, particularly along its southern and south-eastern arc, where the bank is most pronounced. That differential, higher on the exterior than the interior, is exactly what you would expect from a bank built by piling up the soil dug from an accompanying ditch, and it hints at how deliberately engineered these enclosures were. The interior has been planted with trees at some point, giving the old farmstead an almost ornamental quality. More intriguing is a straight-sided cutting in the north-western quadrant, eight metres long, four metres wide, and just over a metre deep. Its regular geometry sets it apart from natural erosion; it may represent a later intrusion into the monument, though its precise origin or purpose is not recorded.