Set on a south-east-facing slope and currently lying within tillage land, it is the kind of early medieval enclosure that can slip past an inattentive eye, read as a vague rise or field boundary rather than what it actually is: the surviving outline of a defended farmstead, probably dating to somewhere between the fifth and twelfth centuries.

A ringfort, or rath, was formed by throwing up a circular earthen bank around a domestic space, creating an enclosure that offered both a degree of protection and a clear statement of social standing. At Garranagoleen, that bank still stands to a height of around 1.1 metres along its south-south-west to east-south-east arc, while a scarp, essentially a slope cut into the ground rather than a built-up bank, does the same work on the remaining circuit. Outside the bank, on the north-west to north-north-east side, a fosse, the ditch from which material was originally dug to build the bank, survives to a depth of 1.4 metres. The interior of the enclosure measures roughly 32 metres across in both directions, making it a reasonably substantial example. Perhaps the most telling detail is a gap on the east-north-east side, some 2.4 metres wide, which almost certainly marks the original entrance, the point through which people, animals, and goods once passed in and out of daily life.