Norwich Castle was built on the instructions of William I and probably included a prison from the beginning.
Francis Blomefield relates that in the 14th year of King Edward III [1340-41]:
“The Earls of counties, who had the custody of the royal castles, often refused to suffer the sheriffs to imprison criminals in the castles, though it had been customary so to do; upon which the legislature took it into consideration, and made an Act of Parliament, that gaols which were wont to be in ward of the sheriffs, and annexed to their baliwicks, shall be rejoined to the sheriffs of counties, and that the sheriffs shall have the custody of the same gaols and prisoners there, as heretofore they used to have; and from this very time, this castle hath been the publick gaol of the county of Norfolk….”
(Francis Blomefield, An Essay towards a Topographical History of the County Of Norfolk (London, 1806) iii, pp85-86).
The county gaol was used to house people awaiting trial at both the Norfolk Quarter Sessions and the Norfolk Assizes.
On 2 August 1887, the prisoners were transferred to a new purpose-built prison on Mousehold Heath (off Plumstead Road) in Norwich and the castle ceased to be used as a prison.
"The County Gaol and House of Correction, commenced in 1824, on the site of the old prison, on the east side of the castle, were completed in 1828, at the cost of £50,000. The governor’s house contains, besides the family apartments, a chapel and committee room.
“Branching from it are three radiating wings, each containing a double row of cells on the ground floor, with a day room next the governor’s house, and double rows of cells on the upper floor. The number of cells in these wings is 240, and there are 36 in the old Keep.
“The diagonals, crossing the radiating wings at right angles, contain only a single row of cells, each having an arcade for the use of the prisoners when the weather will not permit their walking in the yard.
“Behind these are three other diagonal wings, of larger dimensions, with arcades below, and double rows of cells on the upper floor. The mill-house is on the right-hand side of the entrance, and has a machine for raising water (worked by the prisoners) for the use of the establishment.
“The governor’s house being octagonal, and placed in the centre, commands a view of all the wings, day rooms, and yards…..The number [of prisoners] in 1835 was 801, and in 1843, 813.”
(William White, History, Gazetteer, and Directory of Norfolk (Sheffield, 1845) pp. 90-91).
The dungeons in the keep at Norwich Castle Museum and Art Gallery are open to the public and a section of the museum is dedicated to the castle’s past use as a prison. The 19th century prison buildings are used as administrative space.