Others exist, for now at least, only as a faint circular shadow visible from space. In a field of reclaimed pasture in Ballycahill, County Limerick, a possible ditch barrow, a type of prehistoric burial monument typically consisting of a low mound enclosed by a surrounding ditch, has been identified not by any standing feature on the ground but by a cropmark roughly seven metres in diameter, detectable only when viewed from above through satellite imagery.

The site was first noted by researcher Martin Fitzpatrick during analysis of a Google Earth orthoimage dated 5 April 2006. Cropmarks of this kind form when buried features such as ditches or banks affect the growth rate of crops or grass above them, producing subtle variations in colour or density that become legible from altitude, particularly in dry conditions when underlying soil moisture differences are most pronounced. A second, fainter trace of the same circular form was still discernible on a later image dated 14 September 2019, suggesting the feature has some persistence, even if it remains elusive. The site lies approximately 180 metres south of the Camoge River, which at this point forms the townland boundary between Ballycahill and the neighbouring townland of Gotoon. The record was uploaded to the relevant heritage database in July 2021.

There is no meaningful visitor experience here in any conventional sense. The cropmark is not visible from ground level, and the site sits within working agricultural land with no public access or signage. What makes it worth knowing about is precisely its intangibility: a circular trace, about the width of a large room, that may mark a prehistoric burial enclosure and that has so far been noticed only by someone looking carefully at aerial photographs. For those interested in landscape archaeology, the Camoge River corridor in this part of Limerick is worth examining on aerial platforms, where the boundaries between townlands sometimes preserve traces of much older activity along their edges.