It is easy to miss, and easier still to dismiss. But that gently curving bank, eighteen metres long, three metres wide, and rising less than a metre above the surrounding ground, may be the ghost of something once considered very important: an ecclesiastical enclosure, the boundary that would have defined and protected the sacred space of an early Christian site.

Ecclesiastical enclosures are a characteristic feature of early medieval Irish Christianity. Rather than the walled precincts associated with later monastic traditions, these boundaries were often formed from earthen banks or ditches, demarcating the spiritual territory of a church or monastic community and separating it from the secular world beyond. They survive, where they survive at all, as slight humps in the landscape, their original purpose legible only in their curved or roughly circular form. The bank at Aughinish fits this pattern, its arc consistent with the kind of enclosure that would once have surrounded the nearby church. When inspected in June 2007, the bank was measurable but fragmentary; its line could not be traced any further across the ground, suggesting that most of the circuit, if there ever was a complete one, has long since been absorbed back into the island's windswept terrain.

Aughinish Island itself is a remote and exposed place, and that quality of exposure is part of what makes the site quietly legible. There is no infrastructure to mediate the encounter, no interpretive board to explain what you are looking at. The bank lies covered in grass, distinguishable from the surrounding ground mainly by its slight elevation and its curve, the geometry of an intention rather than an accident.