Dún Aonghasa is an iconic prehistoric stone fort situated on a sheer sea-cliff that stands defiantly facing the Atlantic Ocean. It is the largest of the prehistoric stone forts of the Aran Islands, and its construction dates back more than 3,000 years. The fort boasts of three massive drystone defence walls, outside which is a chevaux-de-frise – a dense band of jagged, upright stones that surrounds the entire fort from cliff to cliff, making it a devastatingly effective way to impede intruders.

However, to reach the fort, visitors must embark on a short hike over rising ground, and the last section of the path is over rough, natural rock, which requires care, especially when descending. Therefore, it is recommended to wear boots or strong walking shoes to make the journey more comfortable. Furthermore, visitors should also exercise caution when walking near the cliff as there is no fence or barrier at the edge of the 87-meter drop.

Excavations of the fort have revealed significant evidence of prehistoric metalworking, as well as several houses and burials. In AD 700-800, the whole complex was refortified, making Dún Aonghasa a fascinating archaeological site with a rich history. With its breathtaking views and its position overlooking the sea, Dún Aonghasa is a must-see for anyone with an interest in history, archaeology or just for those who want to experience a truly unique and awe-inspiring natural wonder.