Nottingham Castle is a once-fortified castle in Nottingham, England, later replaced by a Georgian-era mansion. In the Middle Ages it was an important royal fortress and occasional royal residence. In decline by the 16th century, it was largely demolished in 1651. It occupies a commanding position on a natural promontory known as "Castle Rock", with cliffs 130 feet (40 m) high to the south and west. The castle closed for a major refurbishment from 2018 and reopened on 21 June 2021.