This site generates income via partnerships with carefully selected travel brands and/ or purchases made through links to them. As an Amazon Associate I earn from qualifying purchases. See why this is important.Perched atop a high hill in County Donegal, Grianan of Aileach is a stone ring fort built in the 6th or 7th century. Though the site has undergone much restoration, it is still a spectacular place to visit as you can climb the stone steps to the third tier of terraces and view the surrounding Irish countryside for miles and miles.