At Knocknacreha in County Waterford, there is a circular enclosure that has largely ceased to exist, yet has not entirely disappeared. What remains is a shallow, grass-covered depression, roughly 35 metres across, sitting quietly on a south-westerly facing slope. It is the kind of feature you could walk across without realising it was once something deliberate and significant.

The enclosure was recorded on the Ordnance Survey six-inch map of 1840 with a diameter of around 60 metres, and again on the 1926 edition, though by then the measured diameter had reduced to roughly 50 metres. Such circular enclosures are commonly known in Irish tradition as a lios, a term referring to a ring-fort or enclosed settlement, typically of early medieval date, formed by an earthen bank and sometimes a surrounding ditch. Locally, the site at Knocknacreha was indeed called a lios, and at some point approximately thirty years before the site was formally recorded, it was removed, most likely cleared during agricultural improvement. The successive shrinkage between the two map editions hints that the process of erasure may have been gradual rather than sudden. What the 1840 surveyors measured as a substantial enclosure had already lost a quarter of its apparent diameter by the time their successors came around with instruments again.