Situated on the banks of River Medway, Rochester Castle is an impressive Norman tower-keep of Kentish ragstone and a Listed Building I in Rochester, Kent, England. - AsNotedIn

A tower keep castle is a strongly fortified residence in which the keep is the principal defensive feature. The keep may be free-standing or surrounded by a defensive enclosure; they are normally square in shape, although other shapes are known. Internally they have several floors providing accommodation of various types. If the keep has an attached enclosure this will normally be defined by a defensive wall, frequently with an external ditch. Access into the enclosure was provided by a bridge across the ditch, allowing entry via a gatehouse. Additional buildings, including stabling for animals and workshops, may be found within the enclosure. Tower keep castles were built throughout the medieval period, from immediately after the Norman Conquest to the mid- 15th century, with a peak in the middle of the 12th century. A few were constructed on the sites of earlier earthwork castle types but most were new creations. They provided strongly fortified residences for the king or leading families and occur in both urban or rural situations. Tower keep castles are widely dispersed throughout England with a major concentration on the Welsh border. They are rare nationally with only 104 recorded examples. Considerable diversity of form is exhibited with no two examples being exactly alike. With other castle types, they are major medieval monument types which, belonging to the highest levels of society, frequently acted as major administrative centres and formed the foci for developing settlement patterns. Castles generally provide an emotive and evocative link to the past and can provide a valuable educational resource, both with respect to medieval warfare and defence, and to wider aspects of medieval society. All examples retaining significant remains of medieval date are considered to be nationally important.

Rochester Castle was one of the first Norman castles to be fortified in stone, and also has the distinction of being the tallest tower keep in England. The construction of a castle in Rochester can be dated to between 1066 and 1088. Although a large number of these defensive structures were built between the 12th and 15th centuries, many have been lost through factors such as robbing and quarrying, subsidence, modification and adaptation to other uses. Rochester Castle has survived in its original form, and although some features have been lost over time, it still dominates the town, cathedral and the river crossing it was built to defend. No major excavations have been undertaken in the bailey of the castle and this part of the site will therefore contain significant buried archaeological remains relating to the structure of the site, the history of its occupation and the changing fortunes of its inhabitants. - English Heritage