On the brow of a low esker ridge in Ashfield Demesne, County Galway, a cashel once stood overlooking Colman's Lough to the south. A cashel is a type of ringfort defined by its stone enclosure wall, as opposed to the earthen bank of a rath, and this one has left no visible surface trace whatsoever. The ground gives no indication that anything was ever there.

What we know comes from a single cartographic moment. The 1838 edition of the Ordnance Survey six-inch map recorded it as an embanked circular enclosure with an internal diameter of roughly fifteen metres and a maximum diameter of around twenty-seven metres, dimensions typical of a small early medieval farmstead enclosure. These ringforts were the basic unit of rural settlement in Ireland from roughly the fifth to the twelfth century, serving as enclosed homesteads for a single family and their livestock. The esker ridge location is characteristic; eskers, the long sinuous gravel ridges deposited by glacial meltwater streams, offered well-drained ground and natural elevation in an otherwise boggy midland and western landscape. Whether the structure was levelled deliberately, absorbed gradually into agricultural land, or simply eroded over centuries is not recorded. By the time anyone thought to document it in detail, it was already gone.