This one earns it by disappearing. On the Burren plateau near Ballymurphy in County Clare, a circular enclosure roughly sixteen metres across was marked with a confident solid line on the 1916 Ordnance Survey six-inch map, suggesting something solid and legible on the ground at that time. By 1998, when the site was physically inspected, there was nothing to see. The fields around it had been reclaimed, the surrounding land tidied into agricultural use, and whatever had stood there was gone without leaving so much as a shadow in aerial photography.

The enclosure was almost certainly a drystone construction, meaning built from stacked stone without mortar, and most likely raised sometime after 1700. On the Burren, where limestone pavement and loose field stone are essentially the same material in different arrangements, drystone walls can be dismantled and their stone repurposed with very little effort. When land reclamation came to this part of the plateau, a modest circular enclosure would have offered a ready supply of usable stone and no particular reason to be spared. The site was formally listed in both the Sites and Monuments Record in 1992 and the Record of Monuments and Places in 1996, but by then the physical evidence had already been gone for some years, preserved only in the cartographic record of a map made eight decades earlier.