Not because cartographers overlooked it, but because for most of recorded history it simply was not visible. The outline of a sub-circular enclosure, the kind of enclosed settlement that might once have defined a farmstead or a place of some local significance, only became detectable from the air, and even then only barely.

Cropmarks appear when buried archaeology affects how plants grow above it. Ditches filled with looser soil tend to retain moisture, producing lusher, greener growth; compacted foundations do the opposite. Seen from altitude under the right conditions, these variations in a crop can sketch out the ghost of a structure long since levelled. The enclosure at Parknasilloge was captured in exactly this way, identified on an aerial photograph published in the Irish Times on 6th June 2018. A subsequent check against Digital Globe satellite imagery confirmed the outline, though it is described as barely visible even there. Notably, none of the historical editions of the Ordnance Survey six-inch maps, which were painstakingly compiled across the nineteenth century and represent the most detailed record of the Irish landscape at that time, show any monument at this location. Whatever this enclosure was, it left no trace that earlier surveyors could see or record.

The site sits in a category familiar to Irish archaeologists: present in the ground, absent from the archives, discovered almost by accident through a single fortunate alignment of weather, crop, and camera angle. Its shape, sub-circular, places it loosely within a broad tradition of enclosed settlements found across Ireland, though without excavation or further survey, little more can be said about its age or purpose.