Letterkenny (Leitir Ceanainn, "Hillside of the O'Cannons"), county town of Donegal county, lies on rising ground above the River Swilly in the far north of Ireland, overlooking the outflow of the river into Lough Swilly, a 25mi/40km long inlet opening off the Atlantic.
The principal landmark of Letterkenny, a long straggling town on the slopes
of the O'Cannon Hills, is the 215ft/65m high spire of St Eunan's Cathedral (1901), finely decorated with Celtic motifs and stained glass by Harry Clarke and Michael Healy.