These coastal promontory forts, known in Irish archaeology as cliff-edge or coastal dúns, typically date from the Iron Age, though some were used and reused across centuries. The basic principle is elemental. Take a finger of land, cut it off from the mainland with a bank and ditch, and you have a stronghold that requires defending on only one side.

Dundeady sits on the southern Cork coastline, a stretch where such headlands are not uncommon, the geology of the area throwing out jagged promontories into the Atlantic approaches. The fort at Dundeady belongs to a broader pattern of coastal fortification found all along the Irish seaboard, where communities in the late prehistoric and early medieval periods chose these exposed but strategically commanding positions. The cliff faces served as natural walls, and the interior of the promontory provided space for habitation, storage, or refuge. What survives today, as with most of these sites, is likely earthwork rather than standing masonry, the traces of that landward cut still readable in the ground if not always obvious to the untrained eye.