A prehistoric enclosure at Garryroan has been so thoroughly levelled by centuries of agricultural use that it survives now only as a faint swelling in the ground, a roughly circular platform measuring about 36 metres across, with the southern arc marginally more legible than the rest. An enclosure of this type would originally have defined a domestic or ceremonial space, its boundary formed by an earthen bank, a ditch, or both, marking out a world from the land around it. What remains here is the ghost of that boundary, perceptible underfoot rather than to the eye.

The complications do not end with the erosion. When the Ordnance Survey mapped this part of Tipperary for its first edition in 1840, the enclosure was plotted in the wrong position, shown immediately north of a neighbouring enclosure that sits about 30 metres to the south-west. By the time the second edition appeared in 1906, the cartographers had shifted their attention, depicting only the western quarter of the monument, and showing it cut through by a field boundary that no longer exists. Two separate surveys, two separate versions of the same vanishing. The field boundary itself has since disappeared, leaving the land surface with fewer divisions than it had in the Victorian period, though the enclosure it once bisected is no more visible for that.