The site is a rath, the Irish term for a roughly circular earthen ringfort, and this one is oval in plan, measuring approximately 40 metres north to south and 38 metres east to west. What survives is a low bank of earth and stone, worn down enough that the whole thing reads more as a subtle rise in the grassland than as a fortification.

Ringforts were built predominantly during the early medieval period, roughly between the fifth and twelfth centuries, and served as enclosed farmsteads for individual family units. The bank and any associated ditch would have defined a boundary as much social as defensive, marking out a household's space within the agricultural landscape. Thousands survive across Ireland in varying states of preservation, though many have been lost to ploughing, drainage, and road-building, the last of which has claimed part of this example. What makes the Glennafosha site particularly worth noting is the presence within its interior of a cashel, referred to by its site code GA043-088001, a cashel being a stone-walled enclosure distinct from but related to the earthen rath tradition. The co-existence of both monument types within the same footprint hints at a layered history of use or perhaps a site that blended construction techniques, though the poor state of preservation makes it difficult to read the full sequence from the ground.