Knocknatulla Fort, known in Irish as Cnocán na Tulcha, sits on the steep north-east facing slope of Knocknafreaghaun mountain in the Iveragh Peninsula, and it survives now only as a cartographic ghost. Where once a circular enclosure stood, nothing visible remains on the ground.

Ringforts, or raths, are among the most common monuments in the Irish landscape, typically earthen or stone enclosures built during the early medieval period, between roughly the fifth and twelfth centuries, and used as defended farmsteads. Knocknatulla was recorded as a circular enclosure on the first edition of the Ordnance Survey map, which places its documented existence firmly in the nineteenth century. By the time the second edition was produced, the mapmakers had already demoted it, marking it only as "site of", a designation that speaks to erasure, whether through agricultural clearance, gradual erosion on that steep slope, or simple collapse over time. The Irish name, Cnocán na Tulcha, suggests a small hill or hillock associated with a mound, which may itself be a memory of the raised earthwork that once defined the fort's perimeter.

What the vanished fort does leave behind is its position. From the slope of Knocknafreaghaun, extensive views open out to the north and east, the kind of commanding prospect that would have made the site a logical choice for settlement in the first place. Early medieval farmers selecting a location for a ringfort were not indifferent to visibility, either for watching over cattle or for signalling presence in the landscape. The monument itself is gone, but the logic of why someone built there, on a high, outward-facing slope of the Iveragh Peninsula with the land falling away before it, remains perfectly legible.