The monument, a ditch barrow, meaning a low circular earthen mound typically ringed by a shallow enclosing ditch and associated with Bronze Age or Iron Age funerary practice, measures only around five metres in diameter and leaves no obvious impression on the ground. It does not appear on Ordnance Survey Ireland historic maps at all. What confirms its existence is a faint circular cropmark, the kind of pale or dark ring that buried archaeology imprints on growing vegetation when seen from above, readable only when conditions are right and the camera is looking down.

The monument came to attention in a rather roundabout way. On 3 November 1984, aerial photographs were taken along the route of the Bórd Gáis Éireann Curraleigh West to Limerick gas pipeline, catalogued under reference BGE 1/50000 2552. Within that survey, compiled for engineering rather than archaeological purposes, the circular cropmark at Tankardstown was spotted and logged as Site No. 040237. It sits in rough reclaimed pasture, about ten metres west of the townland boundary with Ballincolloo, and forms part of a wider group of barrows recorded in the area under the cluster reference LI040-055001/006. The trace reappeared decades later on OSi orthophotos taken between 2005 and 2012, and again on Google Earth imagery, each time as little more than a suggestion of a circle pressed into the field.

There is nothing to see at ground level in any conventional sense. The site lies in working agricultural land, and access would require landowner permission. The barrow's scale, five metres across, means it would be easy to walk over without registering anything underfoot. Its interest lies almost entirely in what it represents as a piece of the record: a burial monument detected not by excavation or survey on foot, but by a gas company's camera on a winter afternoon nearly forty years ago, and confirmed only by patient examination of overlapping photographic archives. For anyone curious about how much of Ireland's prehistoric landscape survives invisibly beneath ordinary fields, this small cropmark in Limerick is a useful place to start thinking.