This one in the townland of Knockballyfookeen, County Limerick, announces itself with nothing at all, at least to the naked eye. It exists, officially and in the archaeological record, as a roughly oval-shaped cropmark, a faint ghostly outline that appeared briefly in aerial photographs and has since refused to show up again. Cropmarks occur when buried features, ditches, foundations, or filled pits, cause the vegetation above them to grow differently, sometimes lusher where soil has accumulated, sometimes parched where stone or compacted earth lies close to the surface. Seen from altitude under the right conditions, these variations in growth betray the outlines of structures that have otherwise entirely vanished.

The enclosure was identified during the Bruff aerial photographic survey in 1986, recorded under reference Bruff 269 (AP 4/3677). It sits in improved, low-lying pasture that has been cut through by land drains and watercourses, the kind of agricultural tidying-up that tends to erase subtle surface traces over time. It does not appear on any Ordnance Survey Ireland historic maps, which suggests it had already slipped beneath the threshold of visibility long before those surveys were made. What makes the wider area more than just a blank field is the company this invisible monument keeps: two barrows lie nearby, one approximately 30 metres to the north-east and another roughly 55 metres to the north-west. Barrows are burial mounds, typically dating to the Bronze Age or earlier, and their proximity to the enclosure hints at a landscape that was once deliberately arranged, used, and marked by people whose traces are now almost entirely gone. The site record was compiled by Alison McQueen and Vera Rahilly and uploaded in October 2020.

The enclosure was not visible on Ordnance Survey orthophotos from 2005 to 2012, nor on a Google Earth image taken in November 2018, so anyone visiting the area should not expect to see anything that corresponds to the monument itself. The site sits roughly 10 metres south of a trackway and 270 metres east of the townland boundary with Ballyshoneen. The surrounding land is working pasture, privately held and managed, so access is not straightforward. The real interest here is less about what you can see on the ground and more about what the aerial photograph from 1986 briefly revealed: a buried outline in a drained and altered field, sitting quietly beside Bronze Age burial mounds in a corner of County Limerick that modern maps record as simply unremarkable farmland.