Castletown House, Celbridge, County Kildare, Ireland, is a Palladian country house built in 1722 for William Conolly, the Speaker of the Irish House of Commons. It formed the centrepiece of an 800-acre (320 ha) estate.
The estate was sold in 1965, and later sub-divided. The house and a core demesne of 120 acres were bought by a group of people looking to preserve them, and became the first major project of the Irish Georgian Society; they were later transferred to a dedicated charitable foundation, and ultimately to State ownership.