A natural fault running across the isthmus already severed the promontory from the mainland before anyone laid a single stone, leaving an 80-metre neck flanked on either side by a chasm. Whoever built here recognised that a single wall across that narrow passage, combined with sheer cliffs encircling the rest, would create a fortress that geography had half-designed already. A promontory fort of this type works precisely on that logic: a defended headland where the sea or cliff does the work on most sides, and human effort concentrates only where land remains.

The wall that crosses the neck is drystone built, meaning it was constructed without mortar, stone fitted carefully against stone, and it sits on an earthen bank some six metres wide. In front of it runs a fosse, the term for a defensive ditch, approximately six metres across and one and a half metres deep, with a causeway at the entrance and revetting slabs along its inner face. The original entrance was a substantial 12 metres wide, flanked by jambstones, though it has since been partly blocked, leaving a gap of only two metres. A counterscarp bank, the raised outer edge of the fosse, survives along the eastern half. The antiquarian T. J. Westropp described the site in 1912, and earlier observations were recorded by Brown in the 1890s. Both noted the defences were already deteriorating. Westropp further mentioned that the wall had been repaired in 1865 by the then owner, which complicates any reading of what is original and what is restoration. A smaller promontory fort is visible to the south along the same coastline, suggesting this stretch of the Mayo coast was once a landscape of layered, competing occupation.

The interior is wet boggy ground that slopes northward toward the cliff edge, where puffing holes, openings in the rock through which air and water move with the sea below, break the surface near the drop. A low circular mound about ten metres across sits on a rise near the western end. Westropp described circular hut-sites within the enclosure, and while these are not legible from ground level, aerial observation has identified traces of around fifteen. A secondary drystone enclosure abutting the main wall near the entrance may be comparatively recent, as Westropp made no mention of it. The site does not appear as a marked antiquity on Ordnance Survey maps, which perhaps explains why it receives little of the attention that more signposted monuments attract.