Castletown House

On William Conolly's death in 1729, his widow Katherine (née Conyngham) continued living in the house and hosting extravagant entertainments there until her own death in 1752.[3] The Castletown estate then passed to Conolly's nephew William James Conolly, MP for Ballyshannon. On William James' death in 1754 it passed to his son Tom Conolly whose wife, Lady Louisa (great-granddaughter of Charles II of England and Louise de Keroualle), finished the interior decoration during the 1760s and 1770s. Lady Louisa had grown up in Carton House, a demesne to the north east of Castletown house. Much of the work on the interior was carried out to designs of William Chambers. She also did extensive work on the grounds; the paths through the forest are still in walking condition although, due to anti-joyrider measures, several of the culverts have broken and the pathways are again subject to flooding. The drainage scheme through the woodland is ingenious, creating dry paths for walking on land that is below the watertable. The ha-ha fence is part of this intricate network.

When Tom died in 1803 he left the estate to his wife who on her own death in 1821 bequeathed it to her great-nephew, Edward Michael Pakenham, later the MP for Donegal, on condition he adopted the surname of Conolly. He was succeeded by his eldest son, another Tom Conolly, the eccentric MP for Donegal from 1849 to 1876.[4]

Tom's eldest son Thomas inherited Castletown, but after he was killed in 1900 the estate passed to his brother Major Edward Conolly. The Conolly family continued to live in their ancestral house, latterly as the Conolly-Carews, until 1965, when it was sold by The 6th Baron Carew, along with its collections and land, to a Major Wilson for £133,000. Some of the land has been built on, although with some of the estate's features retained amongst the new structures.

The house was bought in 1967 by Mariga and Desmond Guinness for £93,000 to save it from vandalism, became the flagship of the Irish Georgian Society, and was eventually handed over to the newly established Castletown Foundation.

The estate was sold on in parts, with 120 acres (0.49 km²) held as curtilage around the house, some small quantities retained privately by Desmond Guinness, the forested Crodaun Woods part sold to what became Coillte and around 25 acres (100,000 m²) acquired over time by Kildare County Council. Most of the core estate remains as woods or green space but a large fraction in the south west was developed as Castletown Estate, controversially approaching the main house closely, and taking in the Walled Garden and the orchard (whose wall remains), which were lost. However, some other features, such as the Gazebo, the Steward's House and a mock temple, were retained, after negotiations between developer Janus Securities and the Irish Georgian Society.

The charitable Castletown Foundation struggled with the financial and operational demands of maintenance and ongoing restoration, and in 1994, following extensive negotiations between the foundation and the State, Castletown House, with its 120-acre residual demesne, was transferred to the Office of Public Works (OPW).

The OPW continued the programme of restoration, of both house and lands.

Across the broader former estate, and despite the protection of the house and some estate features, at least one of the outlying features, The Gazebo, was partly demolished, without planning permission, in late 2007.[5] An enforcement notice was served on the developer concerned, and further action is expected.[6]

In 2012, work began to restore the lake on the lawn between Castletown House and the Liffey, and this was followed in 2016 by work on the pleasure grounds behind and to the west of the house.