Glenveagh Castle is a 19th century castellated mansion and was built between 1870 and 1873. Glenveagh castle was sited on a small promonotory jutting into Lough Veagh, with fine views along the glen. The building stone chosen was granite, plentiful in Donegal but difficult to work and allowing for little detail. However, the castle's greatest distinction remains its setting.
It was designed by John Townsend Trench, a cousin of its builder and first owner John George Adair, who carried out the infamous Derryveagh Evictions.

Glenveagh National Park is situated on the eastern side of the Derryveagh Mountains in the north-west of County Donegal. The Park contains 14,000 hectares of mountain, raised bogland, lakes and woodlands and is dissected by the valley which gives the park its name, Glenveigh (*Gleann Bheatha*) meaning Glen of the Birches. The Estate was established by John Adair who, in April, 1861 evicted 244 tenants and cleared the land so as not to mar his views of the magnificent landscape. This ignoble history makes the beautiful views all the more poignant for today's visitor. The Park lands include the two highest mountains in Donegal, Errigal and Slieve Sneacht. At the south-west end of the park are the ice-carved cliffs of the Poisoned Glen, a corruption of the name in Irish wich mean 'heavenly glen'. Lough Veagh has natural stocks of brown trout, salmon and artic char. The visitor to the Park can also visit the 19th century Glenveagh Castle with its Neo-gothic architecture complete with ramparts, turrets and a round tower.