This is a rath, the Irish term for a ringfort, the kind of enclosed settlement built in their thousands across Ireland during the early medieval period, roughly between the fifth and twelfth centuries. Farmers and families lived within these circular earthen enclosures, using the raised bank and outer ditch as a boundary against livestock straying and, in more troubled times, as a modest defence. The one at Coolanoran is not ruined so much as reclaimed, swallowed by the vegetation that has colonised it over centuries of disuse.

The enclosure measures approximately forty metres in diameter, defined by an earthen bank and an external fosse, which is the ditch dug to throw up the bank material in the first place. When Denis Power compiled the site record, uploaded in August 2011, he noted that the bank survives to an internal height of around 0.6 metres and an external height of 1.1 metres, which gives a reasonable sense of how it would have dominated the immediate landscape when newly built. The fosse, 1.8 metres wide and still waterlogged, runs around the exterior, though by the time aerial photographs were taken in March 2006, the whole enclosure was buried under dense briars and whitethorn. The only point where the bank and fosse could be approached at all was on the north-east side.

For a visitor, the site is in pasture and the terrain reflects that, which means the usual considerations apply: appropriate footwear, awareness of livestock, and permission from the landowner if crossing private land. The interior is largely impenetrable, choked with thorns, and there is only a small clearing somewhere towards the centre. The north-east approach is the one angle that offers any real view of the earthworks themselves. Aerial photography, as the ASI record suggests, gives a much cleaner picture of the overall form than anything achievable on foot. That is a reasonable summary of many Irish ringforts: more legible from above than from within, their geometry preserved by the very overgrowth that makes them so difficult to actually enter.