Grianan of Aileach (Ireland)

Grianán of Aileach (Irish Grianán Ailigh, English Grianán of Aileach) is the name of a restored stone fort in County Donegal, in the north-west of the Republic of Ireland, about 10 km west of the Northern Irish city of Derry. The Grianán of Aileach was a historic center of culture and politics in the period of Ireland's first rulers (800 BC to 1,200 AD). The fort on Mount Greenan (Grianán) was the seat of the kings of Aileach. The kingdoms of Ulaidh and Airgíalla were sub-kingdoms under Aileach's rule.

Grianán of Aileach is a ring fort built on the site of an ancient hill fort. The Grianán was the residence of the Uí Néill in the 5th century and subsequently owned by the O'Donnell clan. By the 12th century (around 1177), the Kingdom of Aileach had lost much of its lands to the Normans, with the stone fort losing importance and eventually being destroyed by an army under Muirchertach Ua Briain (king of Munster) . The fort overlooks the Inishowen Peninsula to the north. Today it is possible to visit the main bastions, which have a diameter of 23 meters. Other parts of the fort were destroyed, but were restored in the 19th century (around 1870) authentically restored. It is an Irish national monument.