At Ballynabortagh in County Cork, a rectangular enclosure once sat on a north-facing slope in what is now open pasture. There is nothing to see there today, no earthwork, no ridge in the grass, no shadow in a low winter sun. The site has been levelled, leaving no visible surface trace whatsoever.

What we know of it comes from the 1842 Ordnance Survey six-inch map, which recorded the enclosure as a roughly rectangular feature measuring approximately 45 metres on its north-northeast to south-southwest axis and around 40 metres across. Enclosures of this kind in Cork typically served as early medieval farmsteads or settlement boundaries, the rectangular form being somewhat less common than the circular ringfort but not unusual in the south of the county. Intriguingly, a second rectangular enclosure lies about 250 metres to the east-southeast, raising the possibility that the two were related, perhaps contemporary farmsteads, perhaps successive ones. That second enclosure carries its own record, though whether it fares any better on the ground is a separate question.

The site at Ballynabortagh is, in a sense, a lesson in how much of the Irish landscape has been quietly rearranged over the past two centuries. Agricultural improvement, drainage, and ploughing have erased countless features that the early Ordnance Survey mappers were careful enough to note down. The 1842 map captured a moment just before many such sites disappeared entirely, making it an invaluable record of things that no longer cast a shadow.