The ringfort at Boherascrub is a rath, one of the tens of thousands of roughly circular earthen enclosures that dot the Irish countryside, built during the early medieval period as farmsteads for single families or small communities. A bank of earth, sometimes reinforced with timber or stone, enclosed a living area; the external fosse, a ditch dug to throw up that bank, completed the defence. What makes this one quietly arresting is the persistence of its shape across nearly two centuries of mapping, even as the ground around it has closed in.

Ordnance Survey maps from 1842 and 1905 both record the enclosure as a hachured circle, the cartographic shorthand for an earthwork, with a diameter of around 22 metres. By 1905 the external fosse had been captured on paper too, and the 1937 revision still shows the same circular outline, now depicted as a fosse-enclosed area. The site has not changed dramatically in form across those decades; the maps simply caught it at different moments of the same slow, undramatic survival. What has changed is access. Overgrowth has since made the interior unreachable, though the bank and its accompanying ditch remain visible through the vegetation for anyone who gets close enough to look.