Grianán of Aileach is probably the best known monument in Inishowen, County Donegal. Situated on a hilltop 250m above sea level. A beautiful place to visit with and the view from the stone fort of Aileach is breathtaking.
It is a 19th-century reconstruction of a fort believed to have been built by the Northern Uí Néill in the sixth or seventh century AD. Evidence suggests the site was in use before the fort's construction. It has been identified as the seat of the Kingdom of Ailech and as one of the royal sites of Gaelic Ireland.