At Knocknasnaa in County Limerick, a ringfort that was clearly legible on the Ordnance Survey's six-inch map of 1841 has since been levelled, yet it has not quite vanished. What remains is a subtly scarped edge rising to a maximum height of just 0.55 metres and spreading to a width of 4.75 metres, tracing a roughly circular area measuring 28 metres north to south and 32 metres east to west. The ground gives no dramatic signal of what it once was, but the shape is still there if you know to look for it.

Ringforts, sometimes called raths, were the most common form of enclosed settlement in early medieval Ireland, typically consisting of a circular area defined by one or more earthen banks and ditches, used as a farmstead and for the protection of livestock. The Knocknasnaa example was already reduced enough by the mid-nineteenth century to be recorded simply as an embanked enclosure on the 1841 map, suggesting that agricultural pressure had been working against it for some time before that. By the time Denis Power compiled the site record, uploaded in August 2011, the monument had been effectively levelled into the surrounding pasture. A field boundary running on a southwest to northeast axis now bisects the interior, compounding the disruption and making the original plan harder to read as a coherent whole.

The site sits in undulating pasture, and the gentle roll of the land here is actually useful context for understanding what the scarped edge represents; changes in gradient that might otherwise read as natural variation in the ground are, in this case, the last trace of a deliberately constructed enclosure. Visitors looking for the monument should focus on that low, irregular lip of earth rather than expecting any upstanding bank. The interior is level under grass. There is nothing to mark the site formally, so a careful reading of the ground is the only guide available.