Look more carefully, though, and the geometry gives it away: a near-perfect circle, roughly 27 metres across from east to west and 25 metres north to south, defined by an earthen bank and a surrounding ditch that together represent one of the quieter survivals of early medieval Ireland in County Limerick. The site sits on a north-west-facing slope at Knockaunroe, in what is now open pasture, and the engineering behind its construction is subtler than it first appears.

A ringfort, sometimes called a rath, was the standard enclosed farmstead of early medieval Ireland, typically built and occupied between roughly the fifth and twelfth centuries. They were not primarily military structures but rather enclosures that defined a family's territory and provided a degree of security for people and livestock. The Knockaunroe example was surveyed by the Archaeological Survey of Ireland in 2008, and the measurements recorded at that time reveal how its builders adapted the design to the natural contours of the hill. On the southern side, where the ground rises, the bank has been cut back into the slope; on the northern side, where the ground falls away, it has been built up to compensate, keeping the interior at a gentle, workable gradient. The external fosse, a term for the ditch running outside the bank, is nearly seven metres wide and over a metre deep, and is most visible from the east and south-west. Aerial photographs taken by the ASI in August 2000 and January 2003 show the earthwork clearly, its circular outline emphasised by the trees that now grow along the bank. The site remained identifiable in Google Earth imagery as recently as June 2018, compiled as part of a record uploaded by Alison McQueen and Vera Rahilly in July 2020.

The fort sits in private farmland, so access would require permission from the landowner. The tree-lined bank is the most immediately visible feature from outside the enclosure, and the external ditch is easiest to read from the eastern and south-western approaches. Because the monument sits on an open north-west-facing slope, the views outward across the surrounding countryside, noted in the survey as particularly clear to the south-west, west, north, and north-east, give a strong sense of why this particular piece of ground was chosen in the first place.