In the townland of Corrool in County Longford, a circular enclosure was clearly defined enough in the early nineteenth century to be named and drawn, yet today the ground gives nothing away. The pasture is well-drained and unremarkable, and a person walking across it would have no reason to pause.

The site appears on the 1837 edition of the Ordnance Survey six-inch map, one of the most systematic cartographic undertakings ever carried out in Ireland, labelled simply as a fort. In Irish archaeological terms, a fort of this kind typically refers to a ringfort, a circular earthwork enclosure used during the early medieval period, roughly between the fifth and twelfth centuries, most often as a farmstead surrounded by an earthen bank and ditch. Thousands survive across the country in varying states of preservation. This one, it seems, does not survive at all above ground. Whether it was levelled deliberately for agricultural convenience, or simply worn away over the two centuries since the surveyors recorded it, is not known. What remains is a cartographic ghost, a designation on an old sheet of paper pointing toward a piece of ground that keeps its own counsel.