To be privately owned
The Castle can be visited
Holkham Hall

Holkham Hall, a country house and estate, is located in Holkham, Norfolk, England. It is considered an example of 18th-century British Neo-Palladianism, with its austere architecture.
History+
The history of Holkham Hall begins with Sir Edward Coke, who acquired the estate, then known as Neals, in 1609, laying the foundation for the family's wealth. The current building was commissioned by Thomas Coke (1697–1759), later the 1st Earl of Leicester. After a Grand Tour through Europe, particularly Italy, where he likely met architects Richard Boyle, Earl of Burlington, and William Kent in 1715, the idea for the construction matured. Coke initially engaged Colen Campbell, but the oldest surviving plans from 1726 were by Matthew Brettingham under Coke's supervision.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 52.9501, 0.8031