Two steep stream gullies drop away on either side, leaving only a narrow neck of land to defend. Whoever built here did the minimum necessary: they cut a curved ditch of roughly 108 feet along the western side where the natural terrain offered less protection, and raised a substantial earthen mound faced with carefully laid flagstones. A promontory fort is exactly what the name suggests, a defensive enclosure that uses a headland or spur to provide natural barriers on multiple sides, with human-made works only where the land fails to oblige. This one made particularly economical use of the principle.

When the antiquarian T. J. Westropp visited and recorded the site in 1914, he found the stonework in enough detail to measure it: the flagstone facing ran three feet thick, with individual stones between six and ten inches in depth and often two feet square. The whole bank stood eight to ten feet thick and rose six to seven feet above the hollow on one side. An earlier visitor, Coleman, had described it in 1894 as overhanging a wild fissure of the ocean, and recorded that the fort was locally known as Tigey Kehernagh, associated with a giant named Eana Ge Eana, or Geany. That name carried far enough to give the adjacent townland of Ballygeany its identity, and the townland still sits immediately to the east of the fort today. The link between a largely vanished earthwork and a surviving place name is one of those small continuities that keeps old landscape legible, even when the physical fabric is gone.

The site is now inaccessible, so the fort exists mainly in the written record left by those two earlier investigators, and in the name of the land beside it.