The rath at Carrowmore in County Mayo is one such site, a circular earthwork enclosure of the kind that served as a defended farmstead during the early medieval period, roughly between the fifth and twelfth centuries. A rath, to distinguish it from its stone-built equivalent the cashel, consists typically of one or more earthen banks and ditches enclosing a roughly circular area where a family and their livestock would have sheltered. These were not grand fortifications but working farmsteads, the ordinary domestic architecture of early Christian Ireland.

Carrowmore is a placename that appears in several counties across Ireland, derived from the Irish An Cheathrú Mhór, meaning the big quarter, a reference to an old land division rather than any dramatic feature of the terrain. Mayo holds a number of sites bearing this name, and the presence of a rath in such a townland fits a pattern seen throughout the west of Ireland, where early medieval farming communities shaped the land in ways that are still faintly legible from the air or on foot. Beyond its classification and location, the documentary record for this particular site currently holds little that can be drawn upon, which itself says something about how many monuments of this type remain only partially catalogued.

For anyone passing through the area with an interest in early medieval landscapes, the general advice for visiting any unexcavated rath applies here. The earthworks, if visible, are best read at low sun angles, in winter or early morning, when shadows pick out the curves of bank and ditch that flatten into invisibility under bright overhead light. Access to such sites on private land always requires the landowner's permission.