This one is visible only from the air, and even then only under the right conditions. A circular enclosure near Dromore in north Cork exists, as far as current evidence goes, as a cropmark, the kind of ghostly outline that appears in aerial photography when buried ditches affect the growth of crops or grass above them. Photographed in July 1989 as part of an aerial survey, what showed up was the faint trace of a fosse, the term for a defensive or boundary ditch, describing a circle roughly fifty metres across.

Cropmark archaeology works because buried features, whether filled-in ditches, collapsed walls, or old pits, hold moisture and nutrients differently from the surrounding subsoil. In a dry summer, crops or grass over a buried ditch tend to stay greener and grow taller, while those over compacted rubble may scorch earlier. The resulting patterns, invisible at ground level, can be read clearly from above. The Dromore enclosure appears to have been clipped slightly by a field fence to its north-east, and a levelled fence line to the north-west may have disturbed it further. What makes the location particularly interesting is its immediate context: the field directly to the west contains both a ring-ditch and a possible second circular enclosure, suggesting this was not an isolated structure but part of a wider pattern of early activity in this part of the landscape.