The one on a gentle westward-facing slope at Knockroe, near the Lingaun River in south Kilkenny, has two, and they are not equal. The south-western tomb is aligned precisely with the setting sun at the mid-winter solstice, so that at the shortest day of the year light travels down its 3.5-metre passage and reaches the decorated orthostats, the upright stone slabs lining the interior, at the back. The south-eastern tomb, by contrast, is cruciform in plan, a cross-shaped chamber measuring roughly 2.9 by 2.2 metres, and it appears never to have had a passage reaching outward to the kerb of the mound at all. Two tombs, two quite different architectural logics, sharing one roughly circular cairn about 27 metres in diameter.

The cairn itself was not simply piled on the hillside. Excavations carried out over four seasons between 1990 and 1995 established that the builders first scarped the slope to create a raised earthen platform, then laid down a base of boulders, averaging 0.3 to 0.4 metres across, embedded in a dark reddish-purple soil. Above that came a layer of smaller stones, and above that a further layer of small stones that appears to be the result of much more recent field clearance. By 1905 Carrigan had noted a lane cutting straight across the centre of what he called the Coshel, and by the time Ó Nualláin and Cody examined the site in 1987 it was considerably overgrown. The excavations recovered cremated bone from both tombs, with the south-western tomb yielding the larger quantities, along with bone and antler pins, beads, and pendants. Pottery found across the site spans a considerable stretch of prehistoric time: Neolithic Carrowkeel Ware, a type of round-bottomed vessel associated with passage tomb builders, came from the south-eastern tomb, while Beaker pottery, characteristic of a later Bronze Age tradition, turned up between that tomb and the kerbstones, and a Food Vessel was found in the south-western tomb.

The setting gives some sense of how the monument was conceived in relation to the wider landscape. From the cairn, the passage tomb on Kilmacoliver Hill at Baunfree is visible roughly 3.6 kilometres to the south-south-east, and the cairn on Slievenamon, the prominent mountain to the west, can be seen about 11 kilometres away. Whether those visual connections were deliberate is not something the archaeology can settle definitively, but the solstice alignment of the south-western tomb at least makes clear that the builders were paying close attention to what the sky was doing from this particular patch of ground.