This ring barrow in the townland of Kilduff, County Limerick, does almost the opposite. It exists, with reasonable certainty, beneath a stretch of low-lying pasture, yet it has never appeared on Ordnance Survey historic maps, and on a Google Earth image taken in November 2018 it is simply invisible. The monument is known primarily because, on the right day and from the air, the buried remains alter how the grass above them grows, leaving a faint circular trace that cameras have occasionally caught and just as occasionally missed.

A ring barrow is a type of Bronze Age burial monument, typically consisting of a low central mound surrounded by a ditch and sometimes an outer bank. The Kilduff example was first identified as a circular-shaped cropmark during the Bruff aerial photographic survey in 1986, recorded as Bruff 255 (AP 4/3678). Cropmarks form when buried features, such as ditches or banks, influence the moisture and nutrients available to surface vegetation, making the outline readable from altitude, particularly in dry summers when contrast between soil types is greatest. The monument reappeared on orthoimages taken between 2005 and 2015, confirming it had not been a photographic artefact, but it dropped out of visibility again in the 2018 imagery. The site sits in pasture cut through by land drains and watercourses, immediately west of a stream and roughly 195 metres northwest of the townland boundary with Garrison. Two related ditch-barrows lie nearby, one approximately 45 metres to the west-northwest and another about 75 metres to the south-southeast, suggesting this corner of Kilduff once held a small cluster of funerary monuments.

There is nothing to see at ground level, and the site is on private farmland, so a visit in the conventional sense is not really on offer here. The value of knowing about it lies elsewhere. Researchers and anyone curious about landscape archaeology can consult the 1986 aerial survey image and the later orthoimages through the National Monuments Service records, where the site was formally compiled by Alison McQueen and Vera Rahilly and uploaded in October 2020. The monument is a reminder that the Irish midlands and west contain a great deal of archaeology that has never been walked over or officially recorded on a map, and that its existence depends, sometimes entirely, on a dry July and a passing aircraft.