A coastal promontory fort works by letting geography do most of the defensive work: the sea guards three sides, and a rampart or series of earthen banks cuts across the narrow neck of land connecting the headland to the mainland. The result is an enclosure that required relatively little construction to render itself formidable. Dunbur Head carries the traces of exactly this arrangement.

Promontory forts of this type are found at intervals along the entire Irish coastline, and while their precise dates and functions remain debated, they are generally associated with the later prehistoric and early historic periods. Some were likely defensive settlements, others may have served as seasonal refuges or even as enclosures for livestock. The Wicklow coastline, exposed to the Irish Sea and within reach of sea routes connecting Ireland to Britain and beyond, would have made such a position both strategically interesting and practically useful to communities living in the area across many centuries.