Set into undulating grassland in north County Galway, this subcircular ringfort measures roughly 38 metres north to south and 35 metres east to west, and what remains of it has been slowly absorbed into the working landscape around it. A later field wall runs along the outer bank for its entire length, effectively burying it, and along a stretch from east-northeast to east-southeast the outer bank has disappeared altogether. The result is a site that rewards a careful eye rather than a casual glance.

Ringforts are enclosed farmsteads, typically of early medieval date, in which a family and their animals lived within one or more earthen or stone banks for security and social display. This example had two stone-faced earthen banks with a fosse, or ditch, running between them, a double-banked arrangement that would have marked out a household of some local standing. The inner bank is better preserved, surviving in a continuous arc from the northwest around through the east to the southeast, though elsewhere the enclosure is defined only by a scarp, a slope in the ground where the bank has worn away. A gap of about six metres on the southern side may be the original entrance. More intriguing still is a possible souterrain within the interior. Souterrains are underground stone-lined passages, common features of ringfort sites, thought to have served as cool storage spaces or places of refuge. Whether the one at Cappagh is intact, collapsed, or merely suspected from a surface depression, the notes do not say, but its possible presence adds another layer to a site that already carries more history than its battered appearance suggests.