Nottingham Castle is a Stuart Restoration-era ducal mansion in Nottingham, England, built on the site of a Norman castle built starting in 1068, and added to extensively through the medieval period, when it was an important royal fortress and occasional royal residence. In decline by the 16th century, the original castle, except for its walls and gates, was demolished after the English Civil War in 1651. The site occupies a commanding position on a natural promontory known as "Castle Rock" which dominates the city skyline, with cliffs high to the south and west.
William Cavendish, 1st Duke of Newcastle, started to build the mansion in the 1670s; it was completed by his son, the 2nd Duke of Newcastle. This ducal palace was burnt by rioters in 1831, then left as a ruin until renovated in the 1870s to house an art gallery and museum, which remain in use. Little of the original castle survives other than the gatehouse and parts of the ramparts, but sufficient portions remain to give an impression of the layout of the site.
The castle is owned by Nottingham City Council. After a £30 million restoration from 2018, running of the site was undertaken by independent charitable Nottingham Castle Trust with reopening on 21 June 2022. The castle closed again on 21 November 2022 when the trust went into liquidation owing the council £2.68 million, with all employees made redundant by the joint-administrators. The castle and grounds re-opened to visitors on 26 June 2023.
The first Norman castle on Castle Rock was a wooden structure of a motte-and-bailey design, begun in 1068, two years after the Battle of Hastings, on the orders of William the Conqueror. This wooden structure was replaced by a far more defensible stone castle during the reign of King Henry II, of an imposing and complex architectural design, which eventually comprised an upper bailey at the highest point of the castle rock, a middle bailey to the north containing the main royal apartments, and a large outer bailey to the east.