Where Ordnance Survey cartographers recorded a circular enclosure called Lisroe in 1838, and again when the maps were revised in 1916, there is now little more than a faint swell in a field of improved pasture on a gentle rise in County Mayo.

Lisroe is thought to be a rath, the Irish term for a ringfort, a type of enclosed farmstead typically built during the early medieval period, roughly between the fifth and twelfth centuries. They are among the most common archaeological monument types in Ireland, yet they disappear steadily from the landscape through agricultural improvement. This one measured somewhere between twenty and twenty-five metres in diameter according to the mapped evidence, a modest but legible circle that survived on paper across nearly eighty years of cartographic record. Land reclamation eventually did what centuries had not, levelling the enclosure to the point where only a slight circular undulation, still roughly twenty-five metres across, remains discernible at ground level. A field fence crosses it to the north, and a farm road runs immediately to the east, the ordinary infrastructure of a working agricultural landscape having moved through and around what was once a defined, named place.

The name Lisroe itself carries older meaning. Lios, the Irish word for a ringfort enclosure, appears frequently in place names across the country, and its survival here into modern cartography is part of what keeps the site legible at all, even after the earthwork beneath it was almost entirely erased.