Souterrains, constructed typically between the seventh and twelfth centuries, were dug and roofed with large stone lintels, then covered over with earth. Their purpose remains a matter of some debate among archaeologists: cold storage, refuge during raids, or simply a functional annex to a nearby settlement. Whatever the original intention at Kiltycahill, the structure's survival underground is itself the reason it endures at all, sheltered from the centuries in a way that surface-level buildings rarely are.

The townland name Kiltycahill derives from the Irish, and this corner of Sligo sits within a landscape that has been farmed and inhabited since prehistory. Souterrains in the west of Ireland are often found in association with ringforts, the circular enclosed farmsteads that once dotted the countryside in their thousands. The presence of one here suggests that Kiltycahill was, at some point in the early medieval period, a place of settled agricultural life, ordinary enough in its time, though the precise details of who built this particular structure and when remain unrecorded in any available source.