It is not a field boundary or a drainage channel. It is the ghost of a road, a hollow-way worn into the ground over time by the repeated passage of feet, hooves, and wheels, its edges built up by the slow accumulation of displaced material. These sunken lanes are found across medieval Europe, and their depth is itself a kind of record, a measure of how heavily and how long a route was used before it was finally abandoned.

The 1837 edition of the Ordnance Survey six-inch map shows the route clearly, connecting the northeast side of a rectangular bawn to what was then, as now, the public road. A bawn, in the context of Irish tower houses and fortified structures, was an enclosing wall or courtyard that protected the approaches to a castle. Here, the castle in question is Dundonnell, recorded as a rectangular structure sitting in the northern quadrant of just such a bawn. The roadway would once have been the formal approach to that complex, the route by which people, livestock, and goods arrived and departed. Aerial photography still captures it as a legible feature in the ground, approximately ten metres wide along its length. At the southwestern end of the hollow-way, a series of smaller enclosures survives, containing cultivation ridges whose age has not been firmly established, though they hint at an agricultural landscape that once surrounded the castle and its approach.