The trees follow the line of an ancient earthen bank, tracing a path from south through west to north, but beyond that curve the ground gives almost nothing away. No bank, no ditch, no raised profile; just ordinary pasture where the rest of the circle ought to be.

The site is a rath, the Irish term for a ringfort, a type of enclosed farmstead typically dating from the early medieval period, roughly the fifth to the twelfth centuries. Thousands of them survive across Ireland in varying states of preservation, but this one at Parkmore sits at the more fragmentary end of the spectrum. The original enclosure measured around 43 metres in diameter, and a researcher named Rynne, working from topographical files held at University College Galway, recorded the presence of an external fosse, a defensive ditch running around the outside of the bank. That fosse has since vanished entirely from the surface, leaving only the arc of trees as an unreliable monument to the original shape. A gap of about six and a half metres on the south-west side may represent the original entrance to the enclosure, though it is difficult to be certain given how little else has survived.

What the Parkmore rath illustrates, quietly and without drama, is how easily these features dissolve back into the landscape. Centuries of ploughing, grazing, and drainage work can reduce a once-legible enclosure to a faint suggestion, legible mainly to those who already know what they are looking for. The trees, planted along the surviving bank at some point in the intervening centuries, have inadvertently become the site's most reliable record.