Originally built after the Norman conquest to control the strategically important route to the north of England, it played a role in the conflicts of the Anarchy, the First and Second Barons' Wars.

Hugely expanded by Edward I, the castle then fell rapidly into disuse in the late medieval era, its stonework recycled for building purposes in the surrounding colleges.

Cambridge Castle was refortified during the English Civil War but once again fell into disuse, used primarily as the county gaol.

[7] Cambridge Castle remained exposed, however, and Stephen decided to build a supporting fortification at Burwell to provide additional protection.

[10] King John expanded the castle in the years before the First Barons' War of 1215 to 1217, but this work was concentrated on constructing a new hall and chamber, at the cost of £200.

[11][nb 2] During the war, the rebel barons, supported by Prince Louis of France, captured much of eastern England; Cambridge Castle fell in 1216.

[13] The castle was returned to royal control after the war, but Henry III only conducted basic maintenance of the fortification.

[17] More stonework was given away by Mary I in the 16th century for building a mansion at nearby Sawston in the Fens, and other grants of stone given to Emmanuel and Magdalene colleges.

[19] Oliver Cromwell ordered emergency work to be conducted to repair the defences, resulting in two new earthwork bastions being added to the castle and a brick barracks constructed in the old bailey.

[29] The site of the castle bailey and the 19th-century prison is now occupied by Shire Hall, which was built in 1932 as the headquarters of Cambridgeshire County Council.