HMP/YOI Chelmsford was built in the 1830s as a county gaol, close to the centre of Chelmsford. Two new residential units were opened in 1996 (E and F wings) to relieve overcrowding, and a third unit (G wing) was opened in 2006. It serves courts in Essex, taking men whose homes are mainly in the Essex area. It holds those who are sentenced, on remand or on trial. It holds adults, some young adults and also foreign national prisoners.
The oldest part of the establishment houses four wings, A, B, C and D, off a central hub with E F and G being opened more recently.
- A wing is the segregation unit and also holds some key workers;
- B & C wing, general population
- D wing houses vulnerable prisoners
- E wing houses the integrated drug treatment system;
- F wing is the induction unit
- G wing houses a mixed population, particularly older prisoners.
The newer part of the prison has a 12-bed, 24-hour health care unit.