Three sides of the roughly triangular promontory need no wall at all: the rivers wrap around the west, north, and east, and a natural ravine cuts along the eastern flank for good measure. Only the southern, landward approach required human effort, and that effort is still legible in the landscape today as a broad grass-covered bank of earth and stone stretching approximately 175 metres across the neck of the promontory.

The bank itself is substantial: nearly ten metres wide, standing around two metres high on the interior and slightly more on the exterior face. In front of it lies a fosse, which is simply a defensive ditch, roughly five metres across at the top, with a slight berm, a narrow flat shelf, separating it from the base of the bank. Traces of stone cladding survive on the outer edge of the fosse, suggesting that whoever built or maintained this structure was willing to invest in it beyond a simple earthwork. T. J. Westropp, the prolific antiquarian who catalogued so many of Ireland's early fortifications in the early twentieth century, noted the site in a 1918 publication, and it is through his record that the place enters the documentary history. What makes it stranger still is that a fortified church once stood within the enclosed area of the promontory fort itself, a pairing that reflects a pattern found elsewhere in early medieval Ireland, where ecclesiastical communities sought protection behind pre-existing or purpose-built defensive works. The subtriangular enclosed area covers roughly 200 metres on its longer axis and slopes gradually down toward the rounded apex where the rivers converge to the north.