Its earthen banks were long ago ploughed flat, but the outline of the enclosure persists as a ghost in the wheat, where the crop grows differently above the buried remains of the old fosse. A fosse is the defensive ditch that typically encircled a ringfort, and here its presence is legible only from the air, captured in aerial photography as a cropmark, a faint circular signature pressed into the pattern of the field.

By 1934, when a researcher named Bowman recorded the site, the single-ramparted fort was already described as practically levelled, its diameter noted at roughly twenty-nine yards, on land then belonging to a Daniel O'Mahony. The enclosure sits in tillage ground about two hundred and fifty metres south of the River Blackwater. The Ordnance Survey had mapped it twice: once in 1842, showing a roughly circular hachured enclosure, the hachures being the fine lines used to suggest an earthwork in relief, and again in 1938, when the enclosure was measured at approximately twenty metres across. Between those two surveys and the decades that followed, the physical structure was lost to agriculture, leaving the cartographic record and the soil chemistry as the only witnesses.

Ringforts were the most common form of rural settlement in early medieval Ireland, typically enclosing a farmstead and its inhabitants within an earthen bank and ditch. The Boolymore example is modest in scale, a single-ramparted rath rather than a multivallate site, but its survival as a cropmark is a reminder that the landscape holds records the eye alone cannot read.