Dun Aonghasa

Dun Aonghasa stands on the southern cliff of Inis Mor, the largest Aran island, with three concentric drystone walls enclosing a semicircular area whose open side is the cliff edge - a drop of about eighty metres straight into the sea. Building here began in the Bronze Age, around 1100 BC, with major work in the Iron Age. Outside the middle wall is a chevaux de frise: a broad band of thousands of upright limestone slabs set close together to break a charge, one of the best surviving examples in Europe. Whether it was a fortress, a ceremonial enclosure or a status site is argued; excavation found domestic occupation. The walls were partly rebuilt in the 1880s, which is not always made clear. The path from the visitor centre climbs about 900 metres over limestone. There is no fence at the cliff and people have fallen; the edge undercuts in places.

What you actually see

• The cliff edge - the fort's open fourth side, an eighty-metre drop.
• The chevaux de frise - thousands of upright stones set as a defensive band.
• The concentric walls - three drystone enclosures, partly rebuilt in the 1880s.
• The Bronze Age origin - occupation here from around 1100 BC.

When to go

April to October, when ferries and the visitor centre run fully. The path is exposed and the cliff dangerous in wind. Early or late avoids the day-trip crowd from the ferries.

Honest expectations

No fence or barrier at the cliff edge, and it is undercut - people have died here. The approach path is 900 metres of uneven rock, unsuitable for limited mobility. Sections of the walls are Victorian reconstruction.

Nearby

The Worm Hole is on the shore platform below; Kilronan and the ferry are east.