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.


Front perspective view 1 of Dún Aonghasa Stone Fort Front perspective view 2 of Dún Aonghasa Stone Fort Rear perspective view 1 of Dún Aonghasa Stone Fort Rear perspective view 2 of Dún Aonghasa Stone Fort DA Plan Front elevation view of Dún Aonghasa Stone Fort DA Rear Elevation Right side elevation view of Dún Aonghasa Stone Fort Left side elevation view of Dún Aonghasa Stone Fort


3D Model 1

3D Model 2



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High Resolution Data
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Technical Details

3D Capture Method: Terrestrial laser scanning (TLS)

3D Capture Description: Phase based terrestrial laser scanning using a Faro Focus 120 laser scanner. The instrument quotes the following specification:

  • Distance accuracy up to ±2mm.
  • Range from 0.6m up to 120m.
  • Measurement rate up to 976,000 points/sec.
  • Intensity & RGB. Integrated colour camera.
  • Photorealistic 3D colour scans with up to 70 megapixels.
  • Parallax-free colour overlay.

Laser scans geo-referenced using RTK GPS with VRSnow corrections

Data Processing Software

Processing of point cloud data: Faro Scene & Pointools
Meshing of data: Geomagic Studio 2012
3D Modelling & Texturing: Autodesk Mudbox, Mari, 3D Studio Max

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Arts Heritage and the Gaeltacht