It is easy to walk past without registering what you are looking at: a low, eroded bank, a faint depression where a ditch once ran, and a slight narrowing in the perimeter that probably marks where people once passed through. Yet the whole thing describes a coherent enclosure, roughly 40 metres across at its widest, and the logic of its placement on high ground is unmistakeable once you stop to consider it.

This is a ringfort, or at least the earthen remains of one. Ringforts, roughly circular enclosures defined by banks and ditches, are among the most common monument types in Ireland, with tens of thousands recorded across the country. Most date to the early medieval period, broadly between the fifth and twelfth centuries, and they functioned primarily as farmsteads, the bank and fosse offering a degree of protection for people and livestock rather than any serious military fortification. The one at Keelrin follows the usual pattern: a grass-covered bank, widest on the south-west to north-west arc where it measures around seven metres across, reducing to a simple scarp on the north-west to south-east side, with traces of an external fosse, a shallow ditch, running around parts of the circuit. The probable entrance on the south-east side is marked by a gap of about four metres in the perimeter. What makes the Keelrin example quietly interesting is the evidence of how it was absorbed into later agricultural life. At some point the southern perimeter was incorporated into a field boundary running east to west, though satellite imagery from 2013 showed that this later bank had since been removed, leaving the ancient enclosure to stand, eroded but legible, on its own terms again.