12. Dún Aonghasa
Dún Aonghasa, located on Inis Mór in the Aran Islands, is a prehistoric stone fort perched dramatically on a 100-meter-high cliff overlooking the Atlantic Ocean. Dating back over 3,000 years, the fort comprises three massive dry-stone walls and a chevaux-de-frise—a dense band of upright stones—surrounding the entire structure. Excavations have revealed evidence of prehistoric metalworking, as well as several houses and burials. The site is accessible via a 1 km walk from the Visitor Centre, with the last section over rough, natural rock; visitors are advised to wear sturdy footwear and exercise caution near the cliff’s edge. For more information, visit the Heritage Ireland Dún Aonghasa.
