It appears on the 1910 edition of the Ordnance Survey six-inch series, plotted with apparent confidence on a marked slope just to the north-east of the summit. Go looking for it on the ground and you will find nothing. Search for it in aerial photography and, again, nothing. Whatever was there, or was thought to be there, left no trace that modern eyes can recover.

The leading explanation is that the enclosure may have served as a 19th-century artillery observation platform associated with the Glen of Imaal range, which lies to the south-east. The Glen of Imaal has been used as a military training ground since the 1890s, and an elevated position on Lobawn would have offered a direct sightline over the range, making it a practical location for observers to track and record the fall of shot during artillery practice. A temporary structure of that kind, perhaps timber, perhaps earthwork, need not have left any lasting impression on a mountain slope exposed to Wicklow weather. What is more difficult to explain is why a cartographer thought it worth committing to paper in the first place, and as a neat, geometrically precise square at that, rather than a rough or provisional marking.

Lobawn sits within the broader upland landscape of the Wicklow Mountains, and the Glen of Imaal range to its south-east remains an active military area to this day, which affects access to parts of this terrain. The enclosure, if it ever had a physical form, occupied a slope that is otherwise unremarkable, and there is no suggestion that anything is visible underfoot. It is the kind of feature that raises more questions than it answers, a ghost on a century-old map that neither the land nor the sky has seen fit to confirm.