Souterrains, the word comes from the Old French for underground passage, were constructed from stone-lined walls and capstones, dug into the earth beside or beneath a settlement. They served variously as refuges, as cool storage spaces, or as places of concealment during raids. The one at Elmhall is recorded as a known monument, though detailed information about its construction, dimensions, or condition has yet to be made publicly available.

Without more specific documentation on this particular site, the broader pattern of souterrain distribution in Connacht offers some context. Mayo has a significant concentration of early medieval settlement remains, and souterrains in the west of Ireland are frequently associated with ringforts, the circular enclosed farmsteads that once punctuated the landscape in considerable numbers. Whether the Elmhall example follows that pattern, and whether any surface trace remains visible, is not currently known from the available record. It is the kind of site that rewards patient local enquiry as much as formal documentation.