At Corbally in County Mayo, what was once recorded as a probable souterrain, an underground stone-lined passage typically built during the early medieval period for storage or refuge, has since been quietly reconsidered. The site sits within a rath, a circular earthen enclosure of the kind that dots the Irish countryside in considerable numbers, most dating to between roughly the sixth and tenth centuries. These enclosures served as farmsteads, their raised banks offering some protection and a degree of social status to those who built them.

The souterrain classification arose from linear features spotted within the rath's interior on aerial photography. Such features can look convincingly like the telltale outlines of a buried stone passage when seen from above, and recording them as a possible souterrain was a reasonable precaution. On closer analysis, however, the features appear to relate to quarrying activity rather than any subterranean structure. There is no direct evidence that a souterrain ever existed here. The entry in the Sites and Monuments Record has thus left behind a small but instructive example of how archaeological interpretation can shift, not because anyone made an error of carelessness, but because aerial photographs present ambiguous evidence that later examination sometimes resolves differently.