The site under consideration is a rectangular enclosure, roughly 17 metres north to south and around 30 metres east to west, set on a gently south-west-facing slope in undulating grassland within a broad river valley in County Kilkenny.

The enclosure is defined on four sides by different kinds of boundary. To the north and south, earthen banks conjoin it with neighbouring rectangular enclosures, creating a chain of connected spaces rather than a single isolated feature. To the east, the natural topography does the work, with a steep slope forming a ready-made edge. Most intriguingly, the western side runs up towards and abuts a circular enclosure, the round form sitting alongside the rectangular ones in a way that suggests different periods of use, or perhaps different functions, overlapping on the same patch of ground. A further rectangular enclosure, also aligned east to west, lies to the south of the southernmost of the rectangular enclosures, extending the cluster still further. Enclosures of this kind, whether rectangular or circular, are among the most common surviving earthwork forms in the Irish landscape, and their purposes varied widely, from settlement and agriculture to ecclesiastical use and stock management. The grouping at Rathreagh, with its mixture of shapes and shared boundaries, is the sort of arrangement that tends to reward patient attention more than a quick glance.