On the lower eastern slope of Croughaun Hill in County Waterford, a circular patch of grass marks what was once a defended enclosure, its dimensions still measurable and its entrance still legible in the landscape. This is a rath, the Irish term for a ringfort, the most common monument type in the Irish countryside. Thousands were built between roughly the fifth and twelfth centuries, typically as the enclosed farmsteads of single family units, their earthen banks and ditches serving less as military fortifications and more as a statement of land use and social standing. This one at Killerguile is a modest but well-preserved example, sitting close to a west-to-east stream about fifty metres to its south, a detail that almost certainly reflects a deliberate choice by whoever settled here, water being a practical necessity before any other consideration.

The enclosure measures 34.5 metres across in both directions, making it a near-perfect circle. It is defined by a fosse, or ditch, with an outer bank running around the perimeter. The bank survives to an internal height of around 1.2 to 1.4 metres on the stronger northeastern side, though it has been noticeably worn down on the southwestern arc, where cattle grazing has taken a significant toll over the years. The causeway and original entrance gap, 3.3 metres wide, face east, an orientation shared by a great many ringforts across Ireland and possibly connected to practical, symbolic, or simply habitual preferences in early medieval construction. A second rath sits roughly a hundred metres to the north-northeast, and the proximity of two such enclosures to one another is not unusual in areas that were densely farmed during the early medieval period, suggesting this particular hillside once carried a small cluster of related homesteads.