Sometime between 1838 and 1941, a circular enclosure on the Curragh of Kildare quietly disappeared from the map. The first edition of the Ordnance Survey six-inch map, produced in 1838, recorded it clearly: a roughly circular feature approximately fifty metres in diameter, sitting on one of Ireland's most distinctive stretches of open limestone grassland. By the time the revised edition was published in 1941, it was gone, at least from the cartographic record. No visible traces survive on the ground today, and part of the area is now occupied by a military installation.

What that enclosure actually was remains an open question, though the comparison with two nearby ringbarrows offers a reasonable clue. Ringbarrows are a form of prehistoric funerary monument, typically consisting of a low earthen mound enclosed by a circular bank and ditch, and they are reasonably well represented across Kildare. The two surviving examples in the immediate vicinity suggest this lost feature may have belonged to the same tradition, part of a small cluster of monuments that once marked the landscape of the Curragh in a period long before the plain became associated with racehorses and military camps. Whether the enclosure was levelled deliberately, eroded gradually, or simply obscured by later activity is not recorded.

The Curragh has a long history of military use, and that presence has inevitably shaped what survives and what does not. For a feature of this kind, fifty metres across but apparently leaving no earthwork relief, even slight disturbance would be enough to erase it entirely. What the 1838 map captured may have already been faint, a shadow of something much older that the early Ordnance surveyors were careful enough to note before it vanished altogether.