At Cill Fearnóg, a south-facing headland drops steeply from a narrow isthmus, separated from the mainland by a deep, narrow chasm to the west. A short earthen bank and the faint trace of a fosse, the defensive ditch that would once have accompanied it, cross the neck of the promontory, while the remnants of a perimeter bank survive on the headland itself. Taken in isolation, this looks like a single small defended headland, the kind of coastal promontory fort found at intervals all along the Irish coastline, where geography did much of the defensive work and earthworks sealed off the landward approach.

What makes this site more interesting is the wider pattern across the surrounding landscape. Recorded and assessed in 2002 by Casey, the site is part of a sequence of earthworks that, read together, suggest something far more ambitious in scale. On the mainland just inland of the small headland, two parallel banks run halfway across the east-facing headland that comprises Kilfarnoge townland. Three fields further west, a wide levelled earthen bank cuts across the entire headland. When these features are considered alongside more substantial earthworks recorded at nearby Parkmore Point, the cumulative picture becomes one of a large-scale promontory fort operating at the level of an entire headland, with the smaller defended outcrops along the shore serving as subsidiary fortifications or inner citadels within it. Promontory forts, which use a natural coastal projection and close it off with banks and ditches, are generally associated with the Iron Age in Ireland, though many were used across long periods and some were reoccupied or adapted much later.

The earthworks are not dramatic in the way that reconstructed monuments tend to be. They are worn, partially levelled, and scattered across several fields and townlands. The interest is cumulative rather than immediate, and understanding what you are looking at requires holding several fragments of landscape in mind at once, which is, in a way, exactly what the people who built it were doing.