Dun Aengus (Dún Aonghasa in Irish), is the most famous and spectacular of the stone forts on the Aran Islands. It is perched precariously on the edge of the 100m high western cliffs of Inishmore (Inis Mór), the largest of the Aran Islands. The views are spectacular along the limestone cliffs and out over the Atlantic ocean. The cliff fort is a must-see for any visit to Inishmore and is one of the most amazing archeological sites in Ireland.

Dun Aengus consists of 4 concentric semi-circular enclosures. Inside the outermost wall there is a defensive system of jagged limestone slabs planted upright into the ground, known as a chevaux de frise.

Historians still debate the origin and function of Dun Aengus. It may have had a defensive use or been used for ritual purposes.

Dun Aengus is open all year round. It is about 7km by road from Kilronan and is reached by a 20-minute walk along a trail leading from the interpretive centre where there is a small admission charge.