This one, sitting in improved pasture near Patrickswell in County Limerick, does none of that. It exists, as far as anyone can tell from ground level, as ordinary farmland, and it would almost certainly remain entirely unknown were it not for what a camera lens, pointed downward from an aircraft, happened to catch in the summer of 1986.

Cropmarks are the accidental archive of buried archaeology. When underground features such as ditches, walls, or pits lie beneath a field, the grass or crops above them grow at slightly different rates, either lusher over moisture-retaining fills or more stressed over compacted stone, and from altitude those differences read as shadow-lines and colour shifts. The monument near Patrickswell was identified through exactly this process, during the Bruff aerial photographic survey of 1986, recorded as survey reference Bruff 172, AP 4/3605. What the survey captured was a short linear cropmark running roughly north to south, with a small L-shaped cropmark close to its eastern side. Later orthoimage analysis, drawing on Ordnance Survey Ireland imagery taken between 2005 and 2012 and a Google Earth image from April 2013, revealed that these two features appear to form part of a much fainter, roughly semicircular cropmark approximately 25 metres across, curving from west-southwest around through north to east. The site lies around 50 metres northwest of a public road and 200 metres west of the townland boundary with Kilcullane. It does not appear on any OSi historic maps, meaning it left no trace in the cartographic record and was entirely unrecognised until that aerial survey. The record was compiled by Alison McQueen and Vera Rahilly and uploaded in November 2020.

There is nothing to see at ground level, and the site sits within working agricultural land, so access is not a practical matter for a casual visitor. Its interest lies elsewhere, in what it illustrates about how much of Ireland's early archaeological landscape remains invisible until the right conditions, a dry summer, a low-flying aircraft, a careful analyst comparing images taken decades apart, briefly bring it to the surface. The semicircular form, if that reading is correct, might suggest an enclosure of some kind, though the record does not speculate on date or function, and neither should anyone without further investigation.