What makes it more than just a grassy ridge in a working landscape is what lies beneath: a souterrain, one of those dry-stone underground passages or chambers that early medieval Irish farmers built into the ground, most likely for cool storage and possibly as a refuge. The combination of a rath, the Irish term for a ringfort built from earth rather than stone, and a souterrain beneath it is not unusual in the Irish record, but it is the kind of detail that turns an unremarkable field boundary into something considerably older and stranger.

Ringforts were the dominant settlement form of early medieval Ireland, roughly from the fifth to the twelfth century, and thousands survive across the country in varying states of preservation. This one at Kilberrihert measures approximately 48 metres in diameter, placing it in the middling range for the type. Its bank, where it survives to the south and east, is still legible in the landscape, though a field boundary running northeast to southwest cuts across the southeastern side, the kind of incremental encroachment that has reduced or obscured so many similar sites over the centuries of agricultural use. The interior, enclosed by that bank, is where the souterrain was identified, catalogued separately in the county record under its own reference.