Cahernagollum, in County Mayo, contains within it the Irish word caher, or cathair, referring to a stone-walled enclosure of early medieval origin, typically circular and built without mortar. These structures served as farmsteads or fortified homesteads, and they are found across Ireland in their hundreds, though many survive only as low, grass-covered rings that the casual eye might take for a natural rise in the ground. That this particular place carries the name so explicitly suggests the enclosure was substantial enough, or distinctive enough, to define the settlement around it.

Beyond the placename, the specific history of this site remains, for the moment, unrecorded in any publicly accessible form. What can be said is that enclosures of this type in the west of Ireland were generally in use from roughly the early Christian period through the medieval centuries, functioning as protected spaces for a family and their livestock. The western seaboard of Mayo has no shortage of such remains, many of them sitting quietly in rough grazing land, their stone walls reduced to little more than a rubble scatter. Whether the enclosure at Cahernagollum survives in any meaningful form above ground is not currently known from available sources.