Grianán Ailigh
County Donegal

Greenan Mountain was once home to the most powerful fortress in Ulster – the residence of the Kings of Aileach. The ring fort, which today sits on the hill (a 19th century reconstruction true to the original), is only the inner part of what was originally a much larger complex. From the walls of the ring fort you can enjoy panoramic views over green hills and the Lough Swilly.