The new Colchester Union workhouse was built in 1836-37 to designs by John Brown (Colchester Poor Law Union formally came into being on 19th October 1836). Brown was responsible for a number of workhouses in Norfolk including Blofield, Docking and Henstead. Like Henstead, Colchester had a double-cruciform layout with an administration block at the centre, flanked by cruciform male ranges to the east and for women to the west. The long infirmary block, on the north side of the site, was erected in 1848 and later extended several times. Later additions included a laundry (1896), casual wards (1898) and a porter's lodge at the south-east of the site, and a new board-room block to the south.

The workhouse later became Colchester Public Assistance Institution in 1920, then St Mary's Hospital in 1938 which closed down in 1993. After a period of standing derelict, the site has now been redeveloped for residential use.<1>