Dún Aonghasa is a prehistoric stone fort located on the edge of a cliff on the Aran Islands in Ireland. It dates back to around 1100 BC and is one of the most significant archaeological sites in the country. The fort features a massive circular wall made of limestone, which is about 13 meters high in some places, providing stunning views of the Atlantic Ocean. The fort is named after Aonghus, a figure from Irish mythology, and is believed to have been a ceremonial site as well as a defensive structure. Visitors can explore its ancient walls and enjoy the breathtaking scenery, making it a popular destination for tourists and history enthusiasts alike.