What they would be crossing is the remains of a ringfort, a type of enclosed farmstead built in early medieval Ireland, typically between the fifth and twelfth centuries, in which a family and their livestock were protected by a bank of earth or stone and sometimes a surrounding ditch. This one at Clooncullen is easy to miss precisely because time has done its levelling work so thoroughly.

The Ordnance Survey's six-inch map of 1837 recorded the site as a circular enclosure, marked simply as "Fort", which tells us that even in the nineteenth century there was enough visible to prompt recognition. The enclosure is roughly oval, measuring approximately 43 metres on its north-west to south-east axis and 36 metres across the other way. The bank that once defined its boundary survives, but only just: it stands no more than 0.3 metres high and stretches about 3.5 metres wide, much of it worn down to a low scarp on the southern side, where the ground drops away by perhaps 0.8 to 0.9 metres. A fosse, the external ditch that would once have reinforced the enclosure's boundary, was still detectable in a 1976 inspection, but it has since been infilled and is no longer visible at ground level. Where the original entrance once broke the circuit of the bank, there is now no trace.

What remains is essentially a gentle swelling in a field, the kind of subtle topographical oddity that repays a careful eye. The southern scarp is probably the clearest indication of the original structure's shape, offering the best sense of how the enclosure was once defined against the surrounding ground.