Where an early medieval enclosure once stood, a housing estate now occupies the ground, erasing a structure that had endured, at least as a visible earthwork, for well over a thousand years before the twentieth century caught up with it.

Ringforts, sometimes called raths, are among the most common archaeological monument types in Ireland. They were typically circular enclosures defined by one or more earthen banks and ditches, used as farmsteads during the early medieval period, roughly the fifth to twelfth centuries. The example at Cahergal was recorded on the Ordnance Survey six-inch map of 1842, depicted as a hachured circular enclosure with a diameter of approximately thirty-two metres. That mapping, part of the first systematic survey of Ireland, caught the site at a moment when it was still legible in the landscape. Sometime after that, the enclosure was lost to development, and the housing estate that replaced it left no obvious trace of what lay beneath.