 After the abandonment of Rochester 's first castle it was replaced by another on the current site , in the south @-@ west corner of the town walls . Founded between 1087 and 1089 , some parts of the castle survive although it has been much altered by use and reuse in subsequent centuries . William the Conqueror had granted Lanfranc , Archbishop of Canterbury , the manor of Haddenham in Buckinghamshire – which as of the Domesday Survey had an annual income of £ 40 – for the duration of his life . In turn , the archbishop had granted the manor to Rochester 's monks , so on the Conqueror 's death Lanfranc and Gundulf , who was appointed Bishop of Rochester in 1077 , had to appeal for reconfirmation of the original grant from the new king . William Rufus demanded £ 100 in exchange for confirmation of the grant . The two bishops felt such a sum was beyond their means and sought a compromise . Instead it was agreed that Gundulf would build a new stone castle at Rochester . Initially the two bishops were concerned that the cost would exceed the king 's original request and that they would be responsible for the castle 's upkeep . However Henry , Earl of Warwick , convinced them that a castle suitable for the king could be constructed for £ 40 and that following its completion the castle would be handed over to someone else . The actual cost to Gundulf was £ 60 . The bishop was a skilled architect and supervised the construction of the Tower of London 's eponymous White Tower on behalf of William the Conqueror . Gundulf 's castle was adjacent to Rochester Cathedral . According to archaeologist Oliver Creighton , when castles were positioned close to churches or cathedrals it suggested a link between the two , and in this case both were owned by the Bishop of Rochester . Often the same craftsmen and architects would work on these closely related buildings , leading to similarities in some of their features . Along with Durham and Old Sarum , Rochester is one of the best examples of a closely linked castle and religious building . 
