It was not considered notable enough to mark on the Ordnance Survey's six-inch map of 1840, and yet by the time the twenty-five-inch edition was produced, cartographers had recorded it as a raised oval-shaped area defined by a scarp. What exactly it was built for remains an open question.

The monument sits in the north-western quadrant of what may be a wider field system, just east of the boundary with the neighbouring townland of Goatisland, with a barrow complex, a grouping of burial mounds, lying to the north-east. In a 1942 survey, the archaeologist O'Kelly classified it as a Type A earthwork, describing a circular platform with a slightly hollow centre, a surrounding fosse, which is simply a ditch, and an outer bank beyond that. He recorded the platform as standing about 1.2 metres high overall, with a total diameter of around 45.7 metres. Whether the platform ever carried a bank along its own edge, O'Kelly could not determine, and no entrance could be traced. The monument appears in aerial photographs taken in November 1984 during survey work for the Bórd Gáis Éireann gas pipeline, where it reads clearly as a coherent circular form. By the time orthophotography was carried out between 2005 and 2012, the monument had been partially levelled, surviving mainly as a circular shape defined by its fosse.

The earthwork is on reclaimed agricultural ground, and the landscape around it gives little away at first glance. Google Earth orthoimages show traces of a much degraded bank and a wet external fosse, which is perhaps the most reliable guide to its outline today. Visitors approaching on foot should expect soft ground, particularly around the fosse, which retains water. The monument is most legible from above, so comparing satellite imagery before a visit is worthwhile. The nearby barrow complex to the north-east adds context, suggesting this corner of Tankardstown was used repeatedly over a long period for purposes that were more than merely agricultural, even if the precise function of this particular platform has never been established.