At Ballinamona in County Wicklow, on a south-west facing slope that drops sharply away to the south, the 1838 Ordnance Survey six-inch map records a square enclosed feature roughly 48 metres across. By the time later editions of the same mapping series were produced, it had disappeared from the cartographic record entirely, and a physical inspection carried out in 1990 found nothing on the ground to indicate it had ever been there.

The 1838 OS six-inch mapping was among the most detailed and systematic surveys Ireland had ever seen, and features recorded by those surveyors were generally there to be seen. A square enclosure of that scale, approximately the area of a modest field, would not have been a trivial thing to miss or to invent. Enclosures of this kind can have many origins, ranging from early medieval ringforts and their rectangular equivalents to post-medieval farmstead boundaries, garden enclosures, or even temporary military features. Without any surviving physical trace or documentary corroboration, it is impossible to say which category this one belongs to. What can be said is that something significant enough to warrant recording in 1838 had, within a few generations, left no visible mark on the landscape whatsoever.