The estate owes its name to Eustace le Poer, a Norman knight. In 1609 James I granted the land to Sir Richard Wingfield, who was named Viscount of Powerscourt. In 1961, the estate was sold to Mr and Mrs Slazenger. The gardens stand on sloping grounds facing the south side of Sugar Loaf Mountain (503m). They are famous for their magnificent roses and flowering shrubs, the long row of conifers, the eucalyptus copse dating from 1897 and the path of beeches leading up to the front of the house.