That is more or less what happened at Lismoher in County Clare, where a circular feature spotted on aerial photographs was duly catalogued as an enclosure of potential archaeological significance, appearing in official listings through the 1990s. When someone finally walked the ground in 1997, the structure turned out to be a drystone wall of apparently modern construction, enclosing a roughly circular area of about 40 metres in diameter.

The wall itself, standing between one and one and a half metres high, sits in a hazel wood on the northern edge of a small ravine, embedded within a very extensive field system that stretches across several townlands. Drystone construction, which uses carefully fitted stones without mortar, is a tradition with deep roots across the west of Ireland, and walls built in this manner can be difficult to date by eye alone. The setting, a wooded ravine edge within a sprawling ancient field system, gave the site an air of antiquity that the aerial image quietly amplified. It was not until an on-the-ground inspection was carried out that the modern origin of the wall became apparent, prompting a reassessment of what the site actually represents.

What lingers here is not the enclosure itself but the process it illustrates. The Clare landscape is dense with genuine prehistoric and early medieval remains, and distinguishing them from later field boundaries, animal enclosures, or other practical structures built in traditional styles is genuinely difficult work. Lismoher is a small reminder that the map of the past is always being corrected.