Thousands of these enclosed farmsteads were built across Ireland between roughly the sixth and tenth centuries, most consisting of an earthen bank and ditch enclosing a homestead, and the great majority have been damaged or erased entirely by centuries of agriculture and development. At Kilnagnady, the outline of the enclosure has largely melted back into the landscape, leaving only that faint circular trace.

What makes the site more than simply a worn earthwork is what lies beneath it. The interior contains a souterrain, an underground stone-lined passage or chamber of the kind frequently associated with ringforts. Souterrains were typically used for storage, taking advantage of the stable cool temperature underground, though they may also have provided refuge in times of danger. Their construction was deliberate and often sophisticated, with dry-stone corbelling or large capstones spanning the passages. The presence of one here suggests that whoever farmed and lived within this enclosure invested real effort in the site, even if little now remains above ground to show for it.