What survives is a cashel, a ringfort built from drystone rather than an earthen bank and ditch, its roughly circular plan still legible at around 27 metres in diameter. The wall that once defined it runs from east, through south, to west, but from west to north it has been swallowed by a later field boundary, and from north back round to east it has been broken up by generations of field clearance. The stones were simply too useful to leave alone.

This kind of casual erasure is common across the Irish countryside, where early medieval enclosures, most built roughly between the sixth and tenth centuries, were gradually cannibalised for walls, roads, and foundations. A cashel differs from the more familiar earthen ringfort only in its construction material, typically favoured in areas where stone was plentiful and soil thin. What makes the Bullaun example quietly notable is its company: another ringfort lies just 30 metres to the southeast, and a further one sits around 200 metres to the northeast. Three enclosures within such a short distance of one another suggests a settlement cluster of some significance, a small community whose layout has been almost entirely reclaimed by the working landscape around it.