This one in County Limerick reveals itself only from the air, and only under the right conditions. Sitting in rough wet pasture in the north-eastern corner of a cluster of burial mounds near Tankardstown, the earthwork has left no surface trace that any walker or surveyor has been able to detect. What exists instead is an outline, a ghost pressed into the soil, readable only as a cropmark, where the buried remains of a structure cause the grass or grain above it to grow slightly differently from its surroundings.

The site first came to attention on aerial photographs taken on the 3rd of November 1984, during survey work carried out for the Bórd Gáis Éireann gas pipeline. At a scale of 1:5,000, those photographs showed a rectangular-shaped cropmark immediately west of a drainage ditch running north to south. The monument was catalogued as possible site No. 040248, and notably, it does not appear on any Ordnance Survey Ireland historic maps, suggesting it was never recorded through conventional ground-level survey. Later orthophotography taken between 2005 and 2012 showed no visible surface remains whatsoever. A Google Earth image from June 2018 offered another tentative glimpse, this time showing what appears to be a square-shaped cropmark at the same location, though the shape had shifted slightly from the original rectangular outline observed in 1984. A separate image from March 2017 records a farm building immediately to the north of the monument. The site sits within a broader complex of barrows, which are low earthen mounds typically associated with prehistoric burial, adding further weight to the idea that this corner of Tankardstown was once a place of some significance.

Because there are no surface remains, a visit to the area offers little by way of visible archaeology. The site lies in wet rough pasture, and access would require both local knowledge and appropriate permissions from landowners. The cropmark phenomenon is most likely to be visible in aerial or satellite imagery taken during dry summer spells, when soil moisture differences are exaggerated and buried features become legible from above. For anyone with an interest in landscape archaeology or aerial survey, the Google Earth orthoimage dated 28th June 2018 provides the most recent indication of the outline, compiled as part of the record uploaded by Fiona Rooney in May 2021.