Storage, refuge, ventilation for a settlement above, possibly all three at different times; the function of any given souterrain tends to resist a single tidy answer.

The souterrain at Kiltarnaght belongs to a broader pattern of such structures found across Ireland, typically associated with ringforts or early ecclesiastical sites and generally dated to somewhere between the seventh and twelfth centuries. They were built without mortar, the walls corbelled or lined with carefully placed stone, and their low, narrow passages were presumably easier to defend or conceal than any above-ground alternative. Beyond its presence in Kiltarnaght, a townland in the west of Mayo, the specific details of this particular structure remain largely undocumented in any publicly available form.

Given how little is currently recorded about the site, a visitor would be working with almost no guidance on what survives above or below ground, whether the structure is accessible, or how visible it is from the surface. It exists, at least on the map, as a reminder that the Irish landscape holds a great deal that has been noted but not yet fully examined.