They were not discovered through targeted research or local legend but through the practical business of road-building, when the route of the N7 national road between Castletown and Nenagh cut across ground that had been quiet for millennia. What emerged at Cullenwaine, on the border between Offaly and Tipperary North, was something considerably more complex than anyone had anticipated.

The excavation, carried out as Phase 2 work by John Tierney of Eachtra Archaeological Projects, uncovered a dense cluster of prehistoric features across the site known as Cullenwaine 1. Alongside the four cremation pits were ten troughs, two hearths, two ditches aligned north-east to south-west, a post-hole, eleven stake-holes, and three spreads of burnt-mound material. Burnt mounds are a characteristic feature of Bronze Age Ireland, typically consisting of heat-shattered stone and charcoal accumulated around cooking or heating sites, often associated with water-filled troughs. The troughs at Cullenwaine, six of them grouped tightly together at the north-west end of the site, showed no evidence of timber lining. The four cremation pits were clustered nearby, to the south of that trough group, and measured on average 0.7 metres by 0.6 metres. Their fills contained fragments of cremated bone, and four possible pyres were identified in the same north-west corner of the site, suggesting that this area served, at some point, as a defined space for the treatment of the dead. Seven further pits were found in the eastern portion of the site, sitting apart from the burnt-mound deposits and unconnected to the cremation activity.

The site was first tested in 2007 under a separate licence, with the more detailed excavation following as part of a 17.1-kilometre contract commissioned by Laois County Council and the National Roads Authority. It is the kind of place that exists now mainly in the archaeological record, the road having long since been completed and the landscape returned to its unremarkable surface. What Cullenwaine offers is less a place to visit than a reminder of how much prehistoric activity lies just beneath ordinary ground, invisible until a machine cuts through it.