Where the 1838 Ordnance Survey six-inch sheet had carefully recorded a circular embanked enclosure on a low ridge running north-west to south-east near Cloonfane in County Mayo, the later edition had reduced the whole site to a single annotation: 'Cave'. The enclosure itself had been quietly dropped, leaving only a hint that something lay underground.

Ringforts, roughly circular areas enclosed by one or more earthen banks and ditches, were among the most common forms of early medieval settlement in Ireland, typically associated with farming families of some local standing. This one sits on a gentle rise with the ground falling away to the north, a position typical of such sites. At its centre, the 'Cave' marked on both maps is in fact a souterrain, an underground stone-lined passage or chamber that would originally have served the ringfort's occupants, possibly for storage or as a place of refuge. When the site was inspected in 1996, the area was thick with brambles and ferns, and no trace of the enclosing bank could be made out at ground level. The earthworks had either collapsed or been gradually absorbed into the pasture over the preceding century and a half, leaving the souterrain as the only surviving indicator that a settlement once stood here.