The suspected souterrain at Cloghran, a type of underground stone-built tunnel or chamber typically associated with early medieval settlement in Ireland, exists now almost entirely as an absence: not visible at ground level, built over by the North Western Business Park, and known only through the faint traces it left in a photograph taken from the sky.

The evidence comes from aerial reconnaissance. A photograph catalogued as CUCAP BDR 29 revealed three enclosures at Cloghran through cropmarks, the subtle discolorations in growing vegetation that betray buried features below. Within one of those enclosures, researchers identified a distinctively shaped anomaly described as "tadpole" in outline, recorded under the reference DU014-014002. According to Máire Clinton's 1998 study of Irish souterrains, cited in the site notes, this feature is probably the remains of just such a structure. Souterrains were typically used in early medieval Ireland for storage and possibly as refuges, and their curved or elongated ground plans are reasonably distinctive when seen from above, even when nothing survives at the surface.

There is, practically speaking, nothing to see here in any conventional sense. The site sits within a commercial development, and the archaeology, if it survives at all beneath the construction work, is entirely inaccessible. What the Cloghran souterrain offers instead is a reminder of how much of the Irish early medieval landscape persists only in archives, in specialist reports, and in the archives of aerial photograph collections. The CUCAP collection, held in Cambridge, contains many such images of Irish sites, and the cropmark record compiled by researchers like Geraldine Stout represents a kind of shadow map of a country that built largely in timber and earth, leaving traces that only drought, low sun, or altitude can coax back into view.