Four stones arranged in a gentle curve, open to the north, sitting on the floor of a mountain valley in County Waterford. That spare description barely prepares you for what is actually odd about this place: the semicircle is not a freestanding monument but one piece of a dense cluster of prehistoric structures packed into the upper Araglin river valley, as though the builders of different generations kept returning to the same terrain and adding to what was already there.

A kerb circle, in broad terms, is a low ring of upright or recumbent stones that once defined the outer edge of a cairn, the loose rubble mound of a burial monument. When the cairn material disperses over centuries, the kerb stones are often all that survives, left standing as a rough circle or, as here, a semicircle with a diameter of 3.2 metres. This particular example sits at the southern edge of a ravine cut by a tributary stream, close to the point where that stream bends northwest. Within a short distance of it stand a ring-cairn, a circular bank of stones and earth enclosing a flat interior, and a cairn circle, a different variation on the same general tradition of circular funerary architecture. Michael Moore, cataloguing Waterford's prehistoric monuments in the mid-1990s, identified all three as part of a concentrated group, and the proximity is striking: these are not isolated curiosities but elements of what appears to be a deliberately organised upland ceremonial landscape, probably Bronze Age in origin, gathered around the valley of the upper Araglin river.