Lord Powerscourt was keen to make his mark and assert his position as one of importance in society so he set about transforming the medieval castle at Powerscourt into a grand mansion. In 1730 the 1st Viscount Powerscourt (of the third creation) commissioned the German-born architect Richard Castle to build Powerscourt House, a 68 room mansion which was completed in 1741. The mansion was designed around the medieval castle in the style of Palladian architecture and featured baroque dome-roofed towers on either side, giving it in the words of one architectural historian, “the massive dignity of a great Italian Renaissance villa.”
The north front was adapted to present a grand entrance in the Palladian manner, while the south front faced the gardens and was initially only two storeys in height. An extra storey was added in 1787 and further major alterations were made in the late 19th century. The house contained some of the finest 18th century interiors in Ireland and was one of the country’s most beautiful mansions. In 1961, the Slazenger family purchased the Estate from the 9th Lord Powerscourt.