Glenveagh's builder evicted 244 people in three days, a later owner vanished in a storm, and the last owner gave the castle to Ireland

John George Adair, a land speculator, began buying land in Donegal in 1857 and by 1859 held Glenveagh and Gartan, about 28,000 acres. In 1860 his steward, James Murray, was found murdered on a mountain on the estate^†. On 8 to 10 April 1861, with about 200 police and a crew of crowbar men, Adair evicted 47 families from Derryveagh, 244 people including 159 children, and their houses were pulled down^†. Many later emigrated to Australia or America. Adair married the American widow Cornelia Wadsworth Ritchie in 1869 and built Glenveagh Castle between 1867 and 1873. In 1877 he financed the JA Ranch in the Texas Panhandle with Charles Goodnight. He died in St Louis in May 1885, returning from the ranch. The Texas State Historical Association gives 14 May; other sources give 4 May. Cornelia kept Glenveagh until her death in 1921. In 1929 the Harvard art historian Arthur Kingsley Porter bought it. On 8 July 1933 he disappeared during a storm on Inishbofin island; he was presumed drowned and an inquest found he probably died by misadventure. Henry McIlhenny of Philadelphia rented the estate from 1933 and bought it in 1938. He sold the estate to the Office of Public Works in 1975 and gave the castle, gardens and much of the contents to the nation in 1983. The national park opened in 1984 and the castle in 1986. In 2026 the Irish state owns it.