The prison's Victorian B-wing will be torn down
A Nottinghamshire jail is getting a £95m facelift that will double the size of the facility.
Nottingham Prison's capacity will increase from 550 to more than 1,000 prisoners when the construction project is completed in two years' time.
The 250-cell Victorian B-Wing in Sherwood will be demolished and almost 500 new cells built.
The B-wing was closed in the autumn 2005 after a report said it was "unfit for purpose".
Julian Ellis, a member of the Independent Monitoring Board for Nottingham Prison, said the improvements would help create about 100 jobs in the area.
Work on the expansion project has already started.
The Ministry of Justice statement said: "Building work is currently underway at HMP Nottingham and is part of the government's £1.2bn programme to increase prison capacity across England and Wales."
The prison's smaller 30-cell C-wing will also be demolished during the project.
HMP Nottingham opened in 1890 as a city jail but was reconstructed in 1912 and until 1997 served as a closed training establishment for adult males.
In 1997 it became a category B local prison, and currently serves the courts of Nottinghamshire and Derbyshire.
A-wing, which housed 250 prisoners in single cells, was condemned as unfit for human habitation in 2005 and shut.