The enclosure at Knockroe, in the barony of Coonagh in County Limerick, belongs firmly to that category. On the ground, it is almost nothing: a slight swelling of earth, a low bank that barely clears ankle height, an oval outline that the surrounding pasture has been quietly absorbing for who knows how long. What makes it quietly remarkable is precisely the fact that it has nearly vanished, and that the process of vanishing appears to have been well advanced before anyone thought to record it formally.

When the Archaeological Survey of Ireland surveyed the site in 2007, their surveyors found an oval-shaped area measuring roughly 17 metres north to south and about 20 metres east to west, enclosed by a low earthen bank. On its better-preserved western to north-eastern arc, that bank reaches an external height of just 0.25 metres and an internal height of 0.15 metres, with a width of around 4.7 metres. Elsewhere it has been reduced to a scarp, a term for a slope or cut in the ground where a more substantial feature once stood, of only 0.16 metres. The site does not appear on any Ordnance Survey Ireland historic maps, which suggests it had already been significantly levelled or obscured by the time those surveys were conducted. A second enclosure, recorded separately, lies about 60 metres to the south-west, and the site itself sits in reclaimed pasture approximately 30 metres east of a watercourse. Martin Fitzpatrick compiled the record, which was uploaded in April 2021.

By the time aerial orthophotography was captured between 2005 and 2012, no surface remains were visible from above, and the same is true of Google Earth imagery. That near-total invisibility is the central fact a visitor would need to reckon with. The surrounding land is agricultural, the landscape flat and unassuming, and there is nothing to orient yourself against once you are standing nearby. The earthen bank that survives is subtle enough to be mistaken for a natural ground undulation, particularly in summer when grass growth is full. Late winter or early spring, when vegetation is low and raking light catches slight changes in ground level, would offer the best conditions for reading even this much of the site. It is the kind of place that rewards patience and a good map reference rather than casual exploration.