A souterrain, to use the correct term, is an artificial underground structure, typically built during the early medieval period in Ireland, consisting of one or more dry-stone chambers connected by low crawlways. They are found across the country in considerable numbers, yet individually they tend to escape attention, their entrances long collapsed or overgrown, their purposes still debated. Were they storage cellars, places of refuge, or both? The Gortnafolla example carries that same ambiguity.

Beyond its classification as a souterrain and its location in Mayo, the detailed record for this particular site has not yet been made publicly available, which means the specific dimensions, condition, and excavation history of the structure remain inaccessible without specialist inquiry. What can be said is that souterrains in the west of Ireland were generally constructed between roughly the seventh and twelfth centuries, often in association with a nearby ringfort or settlement enclosure. The local placename Gortnafolla, from the Irish, suggests a field or cultivated plot associated with blood or possibly a personal name, the kind of quiet topographical clue that sometimes points towards a longer, more layered history of occupation in a given area.