A circular embanked enclosure, somewhere between twenty and twenty-five metres across, was recorded by the Ordnance Survey in 1838 and then, on every subsequent map edition, quietly vanished. Nothing marks its position at ground level today. No bank, no ditch, no shadow in the grass during a dry summer when buried features sometimes briefly announce themselves. It is, in the most literal sense, a site defined by its absence.

The 1838 Ordnance Survey six-inch map, the first systematic large-scale mapping of Ireland, was produced with considerable care and captured many features of the rural landscape that were already ancient or fading. Circular embanked enclosures of this kind are generally understood to be ringforts, the most common field monument type in Ireland, typically built and occupied during the early medieval period between roughly the fifth and twelfth centuries. A ringfort usually consisted of a raised earthen bank enclosing a domestic farmstead, providing a degree of security for livestock and family alike. That the Killeenrevagh example appeared on the 1838 survey but not on later editions suggests it was already much reduced by the mid-nineteenth century and may have been levelled entirely through agricultural activity in the decades that followed. The land is described as a level expanse of average pasture, the kind of unremarkable ground where earthworks are most vulnerable to the plough and the drainage scheme.