Monument Type: Promontory fort - coastal

Perched at edge of the sheer sea-cliffs on SW side of Inis Mór, Dún Aonghasa, which is a National Monument, is an extensive cliff-top fort, roughly D-shaped in plan.

Dun Aonghasa has an area of almost 6 hectares (14 acres). Three curvilinear walls divide the interior into an outer, middle and inner enclosure; all the enclosing walls terminate at the cliff edge. An additional stretch of wall on the western side appears now to be ‘hanging in space‘ but it must have been an integral part of the defences at one time.

Outside the middle enclosure is a cordon of close-set stone pillars (known as a chevaux de frise). Even today it is very difficult to pass through this barrier.

The original approach to the fort was from the north, parallel to the limestone terraces, and the earliest entrances in the outer and middle walls face in this direction. The modem route (from the north-east) may date back to the Early Medieval period when there was a monastery atthe bottom of the hill where the Visitor Centre now stands.

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Arts Heritage and the Gaeltacht