The castle was built in 1067 and for over one hundred years it was the seat of Government of the Norman Kings. Henry II built a stone keep to house the royal treasury and the Domesday Book. A round tower from the original castle complete with sally ports is still visible. In 1141, during The Anarchy, forces of the Empress Matilda were besieged by the forces of King Stephen at the castle, in the Rout of Winchester.