The rath at Carrownaltore in County Mayo is one such site, a circular enclosure of the kind that served as a farmstead during the early medieval period, roughly between the fifth and twelfth centuries. These structures typically consisted of one or more earthen banks and ditches defining a raised interior area where a family would have kept their home and livestock. The word rath refers specifically to an earthwork version, as distinct from a cashel, which uses dry-stone walling.

Carrownaltore itself is a townland in Mayo, a county whose boggy uplands and Atlantic-facing terrain contain a remarkable density of early medieval and prehistoric remains. The rath here would have been a working agricultural enclosure, the centre of a small family holding in a period when Ireland was organised around tuath, small kingdoms, and the rhythms of cattle farming. The bank and fosse, meaning the surrounding ditch, would have defined social as much as physical boundaries, marking out the household's claim on the land around it. Many such sites were later associated in folklore with the sídhe, the supernatural inhabitants of the otherworld, which discouraged later generations from disturbing them and, incidentally, helped preserve them into the present.