The structure is roughly subcircular, measuring approximately 38 metres north to south and 35.5 metres east to west, and what once would have been a substantial enclosing wall has long since collapsed into a rubble spread across the ground. A later field wall was built directly over it at some point, which says something about how thoroughly the original form had been forgotten, or at least deprioritised, by whoever needed to divide that particular piece of land.

Cashels of this kind were built during the early medieval period in Ireland, roughly between the fifth and twelfth centuries, and typically served as enclosed farmsteads for a single family or small household group. The drystone construction method, using carefully stacked unmortared stone rather than earthen ramparts, was common in the west of Ireland where stone was plentiful and easily worked. At Ballygeagin, a possible entrance gap roughly four metres wide survives on the east-south-east side, which aligns with the general pattern of early medieval enclosures, where entrances were often positioned toward the east. Inside the collapsed perimeter, a low stone mound measuring around 4.5 metres long, two metres wide, and half a metre high remains visible, though its original purpose is not recorded. A modern cattle pen now occupies part of the interior, adding a layer of agricultural continuity to a place that was almost certainly used for livestock management over a thousand years ago.