Many members of the Cumann Chlann Dálaigh, or the O'Donnell Clan Association, were in Donegal Castle in Donegal town on July 5, 2005. Donegal Castle was built 500 years earlier in 1505 by the O'Donnell family. Some history of the O'Donnell chieftains is at the Donegal County Library in Letterkenny.
