A semicircular arc of earthwork, measuring roughly 58 metres from south to north, is all that remains of what was once a complete circular enclosure. The earthen bank still stands to about 0.8 metres in height, and the external fosse, the defensive ditch dug around the outside of the bank, reaches a depth of 1.4 metres. On the northern side there is a counterscarp bank, the low ridge of earth thrown up on the outer lip of the fosse, though this feature may simply be the remnant of a field boundary levelled at some point in the agricultural past. The rest of the circuit has gone entirely, absorbed into the surrounding pasture.

Ringforts, known in Irish as raths when built from earth rather than stone, are among the most common archaeological monuments in the Irish landscape. They typically date from the early medieval period, roughly the fifth to the twelfth centuries, and served as enclosed farmsteads for individual families or small communities. The bank and fosse provided a degree of protection for people, livestock, and stored goods. At Granig, the enclosure was still complete enough in 1842 to be recorded on the Ordnance Survey six-inch map of that year, shown as a hachured circular form, the fine lines radiating inward that cartographers of the period used to indicate an earthen mound or raised enclosure. At some point between that survey and the present, the northern half of the circuit was lost, most likely to agricultural clearance.