Found in County Kildare, Castletown is Ireland's largest and earliest Palladian-style house. It was built between 1722 and 1729 for William Conolly, speaker of the Irish House of Commons and the wealthiest commoner in Ireland. The façade was almost certainly designed by the Italian architect Alessandro Galilei, while the Irish architect Sir Edward Lovett Pearce added the wings.
The house is set amongst beautiful, 18th-century parklands, with river walks, a temple and the remains of the Bathing House. In the 19th century, efforts were concentrated on the immediate environs of the house, with the creation of a formal garden behind the house, and the planting of the yew trees in front of the house. The break up of the estate in the 1960s, however, meant that the immense walled gardens, formerly situated to the north-west of the house have been built upon. These kitchen gardens were by the early 20th century the most profitable aspect of the estate, and a great source of local employment. Today only the farmyard beyond the west wing remains.
In 1994, the house was transferred to State care and it is now managed by the Office of Public Works. The transfer has paved the way for a major programme of restoration and conservation work of the house and demesne lands.