Built by William de Corbeil, Archbishop of Canterbury in 1127. Rochester castle was granted into the custody of William de Corbeil by Henry 1st.
It remained in the custody of the Archbishops of Canterbury until 1215, when, after a seven week siege, the castle was taken into the custody of the crown by King John.
During the late medieval period the castle fell into disrepair and a fire destroyed the floors and ceilings.
James 1st sold it into private hands in 1610 and the castle deteriorated further.
Since 1984 the castle has been in the care of English heritage.
The walls of the keep are 12ft thick and 113ft high to the top of the battlements.