A limestone cave set into a south-west-facing escarpment in County Waterford has been used, revisited, and reinterpreted by the dead and the living across roughly five thousand years. What makes Kilgreany unusual is not simply its age but the layered sequence of human activity that researchers have gradually pieced together: Neolithic burials, a possible Late Bronze Age hoard, and early medieval hearths, all within two modest chambers that remain accessible today.

The cave first came to serious scientific attention in 1928, when E. K. Tratman and colleagues excavated the site and recovered bones of domestic animals alongside those of elk, reindeer, and bear, species associated with the upper Pleistocene. They also found the remains of at least two humans. One of these, a crouched male burial designated Kilgreany B, was initially interpreted by Tratman as Palaeolithic in date, largely because of its apparent association with that ancient fauna. A later re-examination by H. L. Movius in 1935 challenged this, suggesting a Neolithic date was more probable, and radiocarbon dating has since confirmed it: Kilgreany B returned a date of 4820 ± 60 BP. A crouched female burial, Kilgreany A, produced a date of 4580 ± 150 BP, placing both squarely in the Neolithic period. Possibly five further burials come from similar contexts. Notably, the bodies appear to have been laid directly on the cave floor and covered with small cairns, loose stone mounds built over them for partial protection, rather than interred in pits. Fluctuating water levels had disturbed the stratigraphy over the centuries, complicating interpretation, but research published by M. A. Dowd in 2002 drew together the evidence for three distinct phases of use across prehistoric and early medieval time.

The cave itself consists of an outer chamber of roughly six metres by six metres and an inner chamber of approximately four metres by four metres, both standing about four metres high. Both chambers remain accessible to visitors, offering a direct encounter with a space that people returned to, for very different purposes, across several millennia.