It is a souterrain, a type of man-made subterranean structure built during the early medieval period in Ireland, typically consisting of one or more dry-stone chambers connected by narrow creepways and covered over with large capstones. These structures appear across the Irish landscape in considerable numbers, yet individually they tend to attract little attention, partly because so many remain unexcavated and partly because, by their very nature, they are easy to miss.

Souterrains were most commonly constructed between roughly the seventh and twelfth centuries, often in association with nearby ringforts or early ecclesiastical settlements. Their precise function has been debated, though most archaeologists consider them to have served as cool storage spaces, places of refuge, or both. The one at Listernan sits within a part of Mayo that, like much of the west of Ireland, would have been dotted with small farming communities during that period, each managing their landholdings within a social and agricultural framework that the souterrain would have been a practical, if unremarkable, part of. Beyond its classification and location, the specific details of this particular example, its dimensions, its condition, and any associated features, remain unavailable in the open record at present.