Fewer notice what surrounds it: a series of low mound walls, one of which runs east to west and butts directly up against the tomb itself. These walls are not random field boundaries thrown up in some later century. They form part of a prehistoric field system, one that was laid out by the same farming communities who were already treating this landscape as organised, productive ground.

The field system around Poulnabrone is itself only one piece of something much larger. Aerial and satellite imagery has revealed that the network extends northward as far as Corkscrew Hill, and that comparable field systems, carrying both prehistoric and medieval elements, cover most of the Burren uplands. The Burren is a limestone karst plateau in north Clare, and its thin soils and exposed rock have preserved traces of past land use that would have been ploughed away or built over elsewhere in Ireland. What the imagery shows is a palimpsest of boundaries, some prehistoric, some later, overlapping and continuing beneath scrub vegetation where ground survey cannot yet follow. The likelihood is that the visible portions connect to sections still hidden, forming a more continuous and coherent agricultural landscape than any single photograph can capture.

The relationship between the tomb and the field wall is worth pausing over. A portal tomb, sometimes called a dolmen, is a megalithic burial monument typically consisting of upright stones capped by a large flat stone, and Poulnabrone's example is one of the most visited in the country. The fact that a field boundary runs directly up to it suggests that those working this land in prehistory were farming around, and possibly in deliberate relation to, a monument that may already have been ancestral to them. Whether the wall was laid out to honour the tomb, to use it as a convenient marker, or simply because it stood in the way, the proximity alone says something about how these communities understood the land they were dividing up.