That bend is not an accident of modern surveying or a farmer's convenience; it traces the ghost of an ancient oval enclosure that was otherwise bulldozed flat during the 1960s. The road appears to have curved around the monument for well over a century before the earthwork itself was removed, which means the tarmac outlasted the thing it was quietly honouring.

The enclosure was recorded on the first edition Ordnance Survey six-inch map of 1839, shown as an oval roughly forty metres across on its north-east to south-west axis and about thirty-three metres on the perpendicular. Even then, the north-east quadrant had already been clipped by the road. The site sits on poor, marginal ground, the land dropping away steeply to the north toward the river valley below. When the earthwork was levelled in the 1960s, it joined the long list of Irish field monuments that disappeared before systematic protection was widespread. Enclosures of this type, a raised bank and external fosse or ditch encircling a defined interior, are among the most common archaeological forms in the Irish landscape, and are often associated with early medieval settlement, though their dates and functions vary considerably. What made the Ballylarkin example more than a cartographic footnote was what survived underground. Archaeological investigations carried out in 2005, reported by Ó Drisceoil in 2008, located the buried bank and fosse and, more intriguingly, evidence of an internal structure, suggesting that even after decades of levelling, the site retained enough below the surface to tell at least part of its story.