Individually, none of them would draw much attention. Together, they form one of those genuinely odd archaeological puzzles: a cluster of coastal features that may, or may not, represent a series of promontory forts, the kind of defended headlands where Iron Age and early medieval communities placed settlements or refuges at the very edge of the land.

A promontory fort works on a simple principle: nature does most of the defensive work. A headland is already surrounded on three sides by the sea, so a community needed only to cut off the landward neck with an earthwork or ditch to create an enclosed, defensible space. At Ard Na Caithne, the evidence that this happened is frustratingly faint. As recorded by Casey in 2002, the two northernmost headlands retain low earthen banks and the remnants of a levelled drystone wall across their necks. The broad rectangular headland just south of these shows the ghost of a wide, straight bank and a faint fosse, which is the term used for a defensive ditch, now barely legible in the ground. The southernmost headland has a slightly curving fosse that has since been filled in. The middle two are complicated by more recent earthen banks, though earlier features are reportedly visible beneath or alongside them. What Casey concluded was careful and honest: there is not enough surviving evidence to confirm the nature of any of these features with certainty, but all six headlands warrant proper investigation.

What makes this place quietly arresting is precisely that ambiguity. Most archaeological sites offer at least a confident label. Here, the landscape itself refuses to be pinned down, six headlands holding onto just enough of their past to suggest something deliberate happened along this coastline, without quite revealing what.