 The stone @-@ built keeps of the 11th century generally had simple plans , with few rooms and an uncomplicated layout . Rochester 's keep bears testament to a developing complexity , and provides an early example of a keep divided into separate areas for the lord and his retinue . The thickness of the walls allowed rooms to be built into them , as can also be seen at the Hedingham Castle 's contemporaneous keep , or the slightly later one at Dover . The keep 's interior is divided for its entire height by a cross wall running east – west . The ground floor was used for storage , with the three storeys above providing accommodation . The first floor probably contained a hall and great chamber , divided by the cross wall . This level may have been the accommodation of the castle 's constable who looked after it during the owner 's absence . There is a room called " Gundulf 's Chamber " built into the thickness of the wall in the north @-@ west corner ; it may well have been the constable 's private chamber . The second floor contained the keep 's best accommodation and some of its most elaborate decoration . It is 27 feet ( 8 @.@ 2 m ) high and surrounded by a gallery in its upper half built into the thickness of the walls . The floor also had a chapel measuring about 28 by 15 feet ( 8 @.@ 5 by 4 @.@ 6 m ) . At some unknown point in the post @-@ medieval period , a fire gutted the keep , leaving it in its present state without floors or a roof . On the second floor , there are openings in the cross wall , broken by a series of Romanesque columns between round @-@ headed arches . The cross wall carried a well shaft , with a well @-@ head at each floor . The third floor had a second chapel and access to the roof , and may have held additional accommodation . 
