Nottingham Castle dates from the Norman conquest though little of the original castle remains. The castle occupied a commanding position on raised land and was a major fortress during the Middle Ages.
The castle was built on the orders of William the Conqueror though there may have been a Saxon fortress on the site beforehand. Following an initial wooden Norman castle a stone castle was built by Henry II in 1170. Major additions were made to the castle by Edward III and IV as the castle was kept as a royal refuge and a regional symbol of power during the Middle Ages.
As castles fell out of favour after the Civil War it fell into disuse and decay. It was converted into a mansion by the Duke of Newcastle in the 17th century but badly damaged by rioters in 1831 who were protesting the Duke's opposition to parliamentary reform. Since 1878 the castle has been an art gallery and museum.
Thoroton, Robert. 'Section II: Nottingham Castle.' Thoroton's History of Nottinghamshire: Volume 2, Republished With Large Additions By John Throsby. Ed. John Throsby. Nottingham: J Throsby, 1790. 17-33. British History Online. Web. 13 February 2015. http://www.british-history.ac.uk/thoroton-notts/vol2/pp17-33.
About Nottingham Castle. http://www.nottinghamcity.gov.uk/article/22223/About-Us