What remains at Nantinan is a curving earthen bank running from the north-east to the west, wide enough at roughly 3.3 metres to walk along, and still standing nearly 2.6 metres above the surrounding ground on its outer face. A garden shed leans against one side, breeze-block walling abuts another section, and mature trees have taken root along the crest. The southern portion of the interior has been raised by about 0.7 metres to level it against the natural hillslope, and it now functions as a garden. It is an odd domestic arrangement, though not an uncommon fate for this kind of monument.

A rath is a ringfort of earthen construction, typically circular in plan, built and occupied during the early medieval period in Ireland, broadly between the fifth and twelfth centuries. They served as enclosed farmsteads, the bank and any accompanying ditch providing a degree of security for a household and its livestock. The Nantinan example had a diameter of approximately 38 metres when intact. Local knowledge places a probable entrance at the north-north-west, in an area that tends toward poor drainage. The levelled northern half also conceals what may be a souterrain, an underground stone-lined passage or chamber that would have been used for storage or as a place of refuge, a feature found at many ringfort sites across Munster and beyond. Whether that subterranean structure survives intact beneath the disturbed ground is not known.