This one in Coolalough, County Limerick, does none of that. It exists, as far as anyone can tell, only in a single aerial photograph taken in 1986, a faint signal in wet pasture that has since faded back into the ground without leaving anything a visitor could point to and say: there it is.

The site was identified as a possible earthwork during a systematic aerial photographic survey centred on the Bruff area of County Limerick, recorded under reference Bruff 133, AP 5/2079. Aerial survey has been one of the most productive tools in Irish field archaeology since the mid-twentieth century, particularly over low-lying or waterlogged ground where ploughing and drainage have reduced ancient features to crop marks or soil discolouration invisible at ground level. What the 1986 survey captured at Coolalough was enough to warrant recording as a possible earthwork, though the qualification matters: the classification remains tentative. Notably, the feature does not appear on any of the Ordnance Survey Ireland historic map series, which means it either escaped the attention of nineteenth-century surveyors or had already been reduced to near-nothing by the time they passed through. When the same area is examined through modern Google Earth orthoimages, no surface trace is visible at all.

There is, in practical terms, nothing to see at Coolalough today, and that is precisely what makes the record worth knowing about. The site sits in wet pasture, the kind of low, seasonally saturated ground common to this part of Limerick, and the conditions that once preserved a trace of something beneath the surface are the same conditions that now make the land largely featureless to the eye. Anyone with an interest in how Irish archaeology is catalogued and debated might find the case instructive: a single photograph, a cautious identification, and then silence from the ground itself. The compiled record was prepared by Martin Fitzpatrick and uploaded in June 2021, keeping the possibility of something at Coolalough at least open, even if the evidence for it remains stubbornly thin.