Two adjoining enclosures, built from dry stone walls roughly a metre thick and standing to about one and a half metres in height, sit within a broader field system, and between them they contain not one but two souterrains. A souterrain is an underground stone-lined passage or chamber, typically associated with early medieval settlement in Ireland, and their presence here in such density suggests a site that was carefully planned rather than casually accumulated.

The enclosure itself is subrectangular, running approximately fifty metres north to south and forty metres east to west, with a second, similarly rectangular enclosure immediately to its north. One souterrain occupies the north-west corner of the main enclosure, while the other lies within the northern enclosure. The pairing of these underground structures with the paired surface enclosures, all set within a wider organised field system, points to a settlement where both the above-ground and below-ground spaces were deliberately integrated. Souterrains in early medieval Ireland served various purposes, including storage and refuge, and the presence of two within such a compact arrangement is relatively unusual. The wider field system at Lisnanroum adds further context, suggesting this was not an isolated farmstead but part of a more extensive and organised agricultural landscape.