Somewhere in a tillage field in County Kilkenny, about two hundred metres east of the M9 motorway, a circular enclosure roughly seventy metres across has been ploughed so flat that its outline survives only as a cropmark, a ghostly ring that appears in aerial photographs when the soil moisture and the growing crop conspire to reveal what lies beneath. The enclosure's fosse, the ditch that once defined its boundary, shows up in this way because the disturbed earth of an old ditch retains moisture differently from the surrounding soil, and the crops above it grow fractionally taller or greener as a result.

The enclosure was recorded on the first edition Ordnance Survey six-inch map of 1839, which means it was still legible as an earthwork at that point, and it appeared again on the 1947 revision. At some point after that, it was levelled, leaving no surface trace. Aerial photography from July 2000 confirmed that the cropmark remained visible even after the physical monument had gone. The enclosure sat in a landscape that was already busy with related monuments. A ringwork and bailey, a form of Norman fortification consisting of a defended enclosure paired with an attached courtyard, lies roughly four hundred metres to the northeast. Three further enclosures are clustered within five hundred metres to the west and northwest, one of them on the far side of the north-south river valley that runs close to the site. This density of enclosures in a relatively small area suggests a landscape that was intensively settled and organised over a long period, though the precise date and function of the Ennisnag enclosure itself are not recorded.