This one in Raheen, in the Coshlea barony of County Limerick, does the opposite. It exists, as far as anyone can tell, only as a ghost of differential growth in a field of grass, visible not to the naked eye on the ground but to a camera lens mounted on an aircraft passing overhead at precisely the right moment.

The site came to light through an unlikely set of circumstances. In November 1984, aerial photographs were taken during survey work for the Bórd Gáis Éireann Curraleigh West-Limerick gas pipeline. Among the images, at a scale of 1:5000, a circular cropmark appeared in the pasture, sitting immediately east of a relic field boundary. Cropmarks form when buried features, whether ditches, banks, or walls, subtly alter the moisture and nutrient content of the soil above them, causing the vegetation to grow at a slightly different rate or to a different colour, differences that become legible from height, particularly in dry conditions. The circular mark measured approximately twenty metres in diameter, consistent in scale with a barrow, the term used for a prehistoric burial mound. The site sits within a cluster of recorded monuments and had never been noted on the Ordnance Survey's older six-inch maps, which date from the nineteenth century. By the time Digital Globe satellite imagery was captured between 2011 and 2013, only a faint overgrown trace of the same circular form remained. More recent Google Earth images show no surface remains at all. The record was compiled by Fiona Rooney and uploaded to the national monuments database in September 2021.

There is, in practical terms, nothing to see here if you visit in person. The site sits in private agricultural land, and the feature itself has no visible expression above ground. Its interest lies entirely in what its discovery says about the archaeology of this part of Limerick, where monuments cluster in ways that ground-level survey alone would never fully reveal. For anyone curious about the methodology, the aerial photographs held in the Bórd Gáis Éireann pipeline survey archive remain the primary record, and the site entry in the National Monuments Service database, reference LI049-033004, provides the formal documentation alongside the orthoimages that preserve the fading trace.