The example at Carrowkeel in County Mayo is one such site, a rath, which is the Irish term for a ringfort typically constructed from earthen banks rather than stone, forming a roughly circular enclosure that would once have sheltered a farmstead and its inhabitants during the early medieval period, roughly between the fifth and twelfth centuries.

Ringforts of this kind were the basic unit of rural settlement for centuries, home to farming families of varying social rank. A more prosperous household might have surrounded its rath with multiple banks and ditches, while a modest one made do with a single raised earthen ring. The place name Carrowkeel is an anglicisation of the Irish Ceathrú Caol, meaning narrow quarter, a reference to a division of land under the old Gaelic system of territory and ownership. Mayo as a county contains a substantial concentration of such monuments, many of them poorly documented, sitting in fields that have been ploughed, grazed, and built around for generations.

Very little specific detail about this particular site has been formally published or made publicly available, which is itself something worth noting. The fort sits in a landscape where the archaeology is often more present underfoot than it is on any map or screen, and the Carrowkeel rath is, for now, one of those places that rewards the patient and the locally curious more than the casual researcher.