Dún Aonghasa is one of Irelands most visited attractions. Located on the 300ft cliff side or south side of Inismór, It is a semi circular stone fort over looking the Atlantic with daunting and dramatic views that stretch the length of the Island. Dun Aonghasa is deemed to be one of the best examples of its kind in Europe. Archaeologists, scholars and tourists come here from all over the world and it is likely to be given the official status of a world heritage site in the near future. Most people cycle to Dun Aonghasa from the pier and this cycle to Dun Aonghasa has become an attraction in itself due to the eclectic mix of attractions along the way

A 14 acre site the fort consists of three terraced walls surrounding an inner enclosure containing a platform on the edge of a three hundred foot high cliff. The views from it are breathtakingly spectacular. Excavations carried out in the 1990s indicated that people had been living at the hill top from c.1500 BC with the first walls and dwelling houses being erected c. 1100 BC. A remarkable network of defensive stones known as a Chevaux de Frise( c.700bc) surrounds the whole structure.