These are ring-barrows, a type of prehistoric funerary monument in which a low central mound is encircled by a shallow ditch, or fosse, typically dating from the Bronze Age. What makes this group at Knockanpierce quietly remarkable is not any individual feature but the arrangement itself: up to six of them, disposed across the sloping ground in roughly a diamond formation, each one a faint but deliberate mark on the landscape.

The site first came to attention through aerial photography taken in May 1986, when the circular crop or soil marks of as many as nine possible barrows became visible from the air. The question of what exactly is being looked at has not been entirely settled. Circular marks in Irish fields can sometimes be the result of cattle feeding rings rather than ancient monuments, and surveyors noted this possibility here. The variation in dimensions across the group, however, argues against that explanation. Measured individually, the barrows range from around six to nine and a half metres in diameter, with the central mounds themselves between roughly two and three metres across and raised only a few centimetres above the base of the surrounding fosse. These are extremely subtle features, some barely registering as earthworks at all. The most southerly example occupies the highest point of the gently rising ground, and despite being worn away on its eastern side, its mound and western fosse remain legible both on the ground and in aerial imagery.

Visiting requires a certain adjustment of expectations. There is nothing to announce the site; it sits in private farmland behind St Patrick's Terrace on O'Growney Street, and the monuments themselves are so low-lying that they are easily missed even when you are standing among them. The aerial perspective that first revealed them remains, in a sense, the clearest way to appreciate what is there: a quiet, geometric grouping of the dead, holding their arrangement on a slope that the town of Nenagh has grown almost entirely around.