The enclosure at Carrowhall in County Mayo belongs to that category. Marked clearly on the Ordnance Survey map of 1838 as a circular enclosure, it now lies in unremarkable pasture to the west of a road, with no visible surface traces remaining. The ground has closed over it entirely.

Circular enclosures of this kind are common across the Irish landscape and typically date from the early medieval period, roughly the fifth to the twelfth centuries. They are generally interpreted as the enclosed farmsteads of individual families or small communities, defined by an earthen bank and sometimes a fosse, or ditch, around a central living area. The 1838 Ordnance Survey, carried out under the direction of Thomas Larcom, was conducted at a moment when many such features were still legible in the landscape, their earthworks softened but not yet entirely consumed by centuries of tillage and drainage. That the Carrowhall enclosure was captured at that point, and has since been levelled, is itself a small piece of agricultural and landscape history. What the surveyors saw, and thought worth recording, no longer meets the eye in any form.