At Ballyboe in County Tipperary, a circular enclosure sits on a gentle north-east-facing slope of pasture, entirely invisible at ground level. No earthwork rises from the grass, no ditch catches the eye. The only evidence that anything is here at all comes from above.

The enclosure was identified as a circular cropmark on an aerial photograph taken in 1970. Cropmarks form when buried features, such as the filled ditches or compacted soils left by ancient enclosures, affect how plants grow above them, producing patterns in ripening crops or parched grass that are invisible from the ground but legible from the air. The 1970 photograph, taken as part of the Cambridge University Collection of Aerial Photography, captured the outline clearly enough to place it on the record. At some point before or since, a gravel ridge that once ran to the north and north-east of the site was removed, altering the local topography without leaving much trace of its own. What the enclosure originally was, whether a ring fort, a burial enclosure, or some other circular feature of early medieval or prehistoric origin, the evidence does not say with certainty. What is clear is that it was not alone: a second circular enclosure of the same type lies roughly 120 metres to the east, suggesting this gentle slope once held more than the pasture that covers it today.