The site is a univallate rath, meaning a roughly circular enclosure defined by a single earthen bank, the kind of defended farmstead that was being built across Ireland from the early medieval period onwards. This one follows the familiar form closely enough, but what catches the attention is a low oblong mound sitting in the middle of the interior, and, on the southeastern exterior of the bank, a possible entrance to a souterrain that may connect to it.

A souterrain is an underground passage or chamber, usually built from stone and covered with capstones, that was typically used for storage or as a place of refuge. They are found across Ireland in association with raths and other early medieval settlements, and while many were clearly practical, cold-storage structures, others seem to have served more complex functions. At Dromkeen, the earthen bank rises between 1.4 metres and 2.4 metres on its outer face and considerably less on the interior, which is itself a reminder of how these earthworks were designed to project authority outward as much as to defend inward. The interior mound measures roughly four metres by 1.8 metres and stands about 0.6 metres high, modest in scale but conspicuous enough to suggest it was deliberately constructed rather than incidental. The possible souterrain entrance, located in the eastern section of what appears to be accumulated material on the outside of the bank, has not been excavated, so the connection between it and the interior mound remains speculative. It is precisely that uncertainty, a subterranean passage whose extent and purpose are still unknown, that gives the site its quiet pull.