This one is remarkable for what it no longer does. A small circular earthwork once stood in Tonaknock, in north County Kerry, of the kind known as a rath or ringfort, a type of enclosed farmstead typically built during the early medieval period, roughly between the fifth and twelfth centuries. Thousands of them survive across Ireland in varying states of preservation. This particular example does not survive at all.

The enclosure was recorded on the Ordnance Survey maps of 1841 to 1842, which means that mid-nineteenth-century surveyors could still make it out on the ground. By the time the 1916 edition of the same maps was produced, it had already vanished from the record, and nothing of it remains today. The site lay to the south of a neighbouring monument, suggesting it was once part of a local cluster of earthworks in the area. C. Toal's North Kerry Archaeological Survey, published in 1995, is the source that preserves even this much of its existence.

What makes the site quietly worth knowing about is the gap it represents. The seventy-odd years between the two map editions were a period of considerable land change across rural Ireland, encompassing famine, land clearances, agricultural consolidation, and shifting patterns of land use. Earthworks that had endured for over a millennium could disappear within a generation under a plough or a drainage scheme. The Tonaknock rath left no visible trace, only a map notation and a catalogue entry to indicate it was ever there.