At Shinanagh in north County Cork, what appears to be a circular enclosure some thirty metres in diameter has never been excavated, never been mapped at ground level, and may not be visible to anyone standing in the field itself. Its existence is known almost entirely from a single aerial photograph.

The photograph, taken in July 1989 as part of the Cambridge Aerial Survey of Archaeological Programmes, captured a cropmark tracing an arc of a fosse, the filled-in ditch that once formed the boundary of a circular enclosure, running from east around to north-north-west along the southern side of a field fence. Cropmarks form when buried features such as ditches or walls affect how plants grow above them; a filled ditch retains more moisture and nutrients, so the crops above it grow taller or ripen at a slightly different rate, making the outline legible from altitude even when nothing breaks the surface. The arc at Shinanagh is consistent with the remains of a ringfort or similar enclosed settlement, the kind of circular farmstead that was common across Ireland from roughly the early medieval period, though without excavation the date and precise function of this one remain uncertain.