Roughly fifteen metres across, it was built using a drystone double-wall technique with a rubble core, a method that appears across many centuries of Irish construction and offers no easy clues about when someone first chose this particular spot to shelter. The form itself, subcircular rather than perfectly round, is the kind of shape that turns up in early medieval and prehistoric contexts alike, which is precisely why its age remains undetermined.

What complicates the picture further is visible in the south-eastern sector of the structure, where a later rectangular building was put up directly against or over the older walls, damaging them in the process. This layering of one building tradition onto another is common enough in Irish archaeology, rectangular construction having gradually displaced the older circular or oval forms over many centuries, but it is rarely so legible on the ground. The site sits in Fawnmore, on Inishbofin, the island off the Connemara coast in County Galway, and whatever its original purpose, the remains suggest a place that was returned to and reused across a long, unrecorded span of time.