The ringfort at Dromdrasdil is modest in scale, roughly twenty metres across from north to south and twenty-four from east to west, but what gives it a quietly unsettling quality is what lies beneath it: a souterrain, the term for an underground stone-lined passage or chamber, typically associated with early medieval settlement and used variously for storage, refuge, or both.

The fort itself belongs to the rath type, an enclosure formed by an earthen bank rather than a stone wall. Here the bank survives to a height of roughly 0.9 metres, with a shallow external fosse, essentially a ditch, running along the western, northern, and eastern sides. The entrance gap to the south-east, just 1.4 metres wide and defined on its western side by a large boulder, would once have controlled all movement in and out. Whoever built this place was attentive to the hillside: the interior has been raised slightly on the northern and eastern sides to level out the natural eastward slope. The boulders piled onto the bank to the south-south-west appear to have been dumped there at some later point, suggesting the site was used, modified, or simply encroached upon long after its original occupants were gone. The conifers now planted inside the enclosure add another layer of later alteration, obscuring both the interior ground surface and any sense of how the space would once have felt.