Lismore Castle has been the Irish home of the Dukes of Devonshire since 1753. It overlooks the Blackwater Valley with views over rolling, wooded hills to the Knockmealdown Mountains beyond. The historic gardens are divided into two very different halves. The Upper Garden is an example of the 17th century walled garden first constructed here in about 1605. The outer walls and terraces remain and the plantings have changed to match the tastes of those living within the Castle. The Lower Garden was constructed in the 19th century and is informal with shrubs, trees and lawns, while the stately Yew Avenue is much older, perhaps from the 17th century.