Carlisle Castle was founded in the late 11th century by William II, the son of William the Conqueror, when the region was still part of Scotland. The ejection of the Scots lead to centuries of border conflicts with the castle changing hands many times. The current stone keep and walls were built to replace the original Norman motte and bailey castle on the orders of Henry I in 1122. 

The 900 year old fortification has also been the subject of a number of wars and invasions. In 1644 it was the setting for a long siege by Parliamentary forces, during the English Civil War. It was later involved in the second Jacobite rising against George II in 1745, when it was briefly captured before being retaken by the opposing sides. By the mid-18th century it had become redundant and neglected although was latterly used as an Army depot. Today it is in the care of English Heritage.