A large subcircular enclosure, measuring roughly 60 metres north to south and 55 metres east to west, was recorded on the Ordnance Survey six-inch maps, but nothing of it can be seen on the ground today. No bank, no ditch, no earthwork of any kind survives above the surface. The land has simply moved on without it.

Enclosures of this general type are scattered across Ireland, and they range considerably in date and purpose, from early medieval ringforts used as farmsteads and defended homesteads to prehistoric ritual or agricultural boundaries. Without excavation it is impossible to say which category this one belongs to. What the maps do tell us is that the enclosure sat on the slope of a glacial ridge, the kind of long, rounded landform left behind by retreating ice sheets, and that later field boundaries were laid across it from the east to the southwest, gradually obscuring and eventually erasing whatever physical trace remained. The pattern is a familiar one in the Irish landscape: centuries of agriculture quietly dismantling what earlier centuries built.

There is nothing to see at Knockogonnell now, which is in its own way the point. The site survives only because someone cross-referenced an old map with the terrain and noted the shape before it disappeared entirely from living memory. That act of recording is often the last thing standing between a place and complete oblivion.