This is a rath, the Irish term for a ringfort, the most common monument type surviving in the Irish landscape. These enclosures, typically built during the early medieval period between roughly the fifth and twelfth centuries, were the farmsteads of farming families, defined by one or more banks of earth thrown up from an accompanying ditch, or fosse. The example at Knockadigeen is a bivallate type, meaning it has two concentric banks with a fosse between them, which places it among the more substantially defended end of the ringfort spectrum.

The earthwork measures approximately 26.5 metres north to south and 23.5 metres east to west, making it a modestly sized but well-defined enclosure. The inner bank stands around 1.28 metres above the interior ground level and slightly less on its outer face, while the fosse between the two banks is wide and U-shaped, reaching over two metres in depth and more than four metres across. An outer bank beyond the fosse adds a further layer of definition to the whole. The asymmetry of survival is telling: the western and downslope portions of both banks are in noticeably better condition than the south-eastern quadrant, where the outer bank has been destroyed entirely. No formal entrance survives, though a cattle break in the western sector carries a faint suggestion of an original causeway crossing the fosse, the usual means of access in ringforts of this kind. The interior slopes gently westward and has suffered some disturbance from animal burrowing, and scrub now covers the inner bank and fosse along the southern arc.