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. Rochester Castle, which includes a tower keep, a bailey with a curtain wall and an outer ditch, dominates the point where the Roman Watling Street - originally the main road between Canterbury and London - crosses the River Medway. Although the castle dates from the immediate post-Conquest period and has a well-documented history from its foundation onwards, the earliest occupation of the site is likely to have been in the Roman period. The western curtain wall overlies an earlier Roman wall at this point, making it likely that the area of the castle was once within the Roman town of Durobreve. The earliest references to the castle are in Domesday Book - where it is recorded that the Bishop of Rochester had been given land in Aylesford 'in exchange for land on which the castle stands' - and in the Textus Roffensis, where the land on which the castle was built is said to be 'the best part of the city'. The first fortification of the site in stone is generally accredited to Bishop Gundulf after the siege of 1088. The wording of the agreement for work to be carried out also implies that an earlier castle, not built of stone, originally occupied the site, although no trace of this structure has yet been identified. The four-storeyed stone keep, one of the largest in England, is 21m square with walls up to 3.5m thick and 34.5m high to the top of the parapet. The south east corner of the keep has been rebuilt, probably as a result of the breaching during the siege of 1215. To the north of the keep, an irregular bailey, some 120m from north to south, is now partly defined by the curtain wall which once enclosed it; this survives on the west side of the bailey where it is all that can be seen of the Gundulfian period of construction. This section was built on top of the foundations of the Roman city wall and was subsequently altered in the 13th century. A long section of the curtain wall on the south side of the castle was demolished in modern times, but at the east end a section of wall with drum towers (the work of Henry III) survives. Beyond the curtain wall on the landward side, but only now visible to the east and north of the castle itself, are the remains of the castle ditch. Although this has been partly infilled and built on over the years, it still survives as a relatively deep buried feature. Below the levels of modern disturbance, deposits will survive providing evidence for the occupation of the site and the environment and economy of the surrounding area. It has been suggested that a second bailey existed immediately to the south west of the keep. However there is currently no confirmation of this and the area is not included in the scheduling. In 1127 Henry I gave the custody of Rochester Castle to the Archbishop of Canterbury and his successors, and shortly after this Archbishop William de Corbeuil began the construction of a stone keep in the southern part of the bailey. Various repairs to the castle and town defences are recorded in the Pipe Rolls for 1166-1167, 1170-1171 and the castle itself was strengthened during the reign of Richard I (1189-1199). During the siege of 1215, the curtain wall and the south east corner of the keep were undermined by King John's engineers, and the castle eventually fell to the besiegers. Subsequently, urgent repairs were made to the keep and the curtain wall, with the tower on the south east angle being rebuilt between 1221 and 1222 on a circular plan, thereby making it much more difficult to undermine. In 1237 mention is made of a southern gateway to the castle wall and the construction of a drawbridge - no trace of which can now be seen. In 1264 the castle was subjected to another siege, when Earl Warrene and Roger de Leybourne held it for the king against Simon de Montfort and Gilbert de Clare. The barons breached the city wall and the outer defences of the castle, but the great keep held out and they were eventually forced to withdraw. Little effort was made to repair the damage caused by this onslaught, and in the 1340 survey made for Edward III, it was reported that there were 'dilapidations over the whole extent of the castle'. Thus in 1367 a programme of rebuilding was begun. Of the two mural towers to the south of the main gate on the east of the castle, the northernmost was built new at this time and the southern one was rebuilt. By 1370 the programme was complete. Between 1378 and 1383, a new tower was built on the north angle of the curtain wall. Further demolitions and alterations are known to have taken place c.1872. The keep and curtain wall are Listed Grade I, and are included in the scheduling as is the ground beneath them. (Scheduling Report)
Castle Keep, curtain walls and mural towers to bailey. A building of exceptional significance. Built at the bridging point where Watling Street crosses the Medway. One of the first Norman Castles to be fortified in stone. Bailey walls, 1087-9, built by Gandulf, Bishop of Rochester for William II; keep, 1127, built by Archbishop William of Corbeil, considerable rebuilding and repairs throughout, 1221-32 (after the 1216 siege) and again by Edward III and Richard II, 1367-83; some demolition and alterations, c.1872. Mainly Kentish rag with tufa and chalk rubble. The building is described in detail by R Allen Brown (1986) which should be consulted for further information. Gandulf's curtain wall survives to the W(Mersey side) and incorporates remains of the Roman city wall (see Refs 7/2 and 9/2); strengthened in C13. SE section, including the drum tower, mid-C13; E section (C14) includes 2 curtain walls, one of which (now a cottage) contains vaulted room, spiral stone stair and 2 garderobes. N section of wall, fragmentary, is incorporated into the garden walls to the rear of High Street properties. The N perimeter wall of the present castle precinct is marked by a C20 wall with palings. To the NW, the bastion (1378-83), altered and breached by a prominent Norman-Revival round-headed arched entrance of c1872. Keep, roofless and without principal floors, rectangular on plan with corner turret (that to SE in circular form, Mid C13) and contempotary forebuilding (with chapel and chambers) to N reached from W at 1st floor level. Main building consists of ground-floor basement; 1st floor apartments; great hall and chamber occupying 2 storeys; private apartments above, all divided by massive cross wall pierced by doorways and (at great hall level) a 4-bay arcade. It contains a well shaft. NE stair to all floors; SW stair excludes access to basement. Decoration sparingly applied: externally to principal doorways and upper floor embrasures; internally mainly chevron with some shafting; arcade with scalloped capitals. (Listed Building Report)
It is important to realise the Great Tower was built as a palace for the Archbishop (or even as a joint palace for the archbishop and the king), a place for him to show his might as a great land lord, as well as a religious leader, and to receive homage from his numerous retainers. It was no more designed or built to be a place of last resort in a siege than the grain silos of Stalingrad in 1942/3. As a massive and strongly built tower it could be used as a last resort, as it was in 1215, but explanations of the architectural features, such as the forebuilding, in terms of resisting a siege are misleading and only obscure the way the tower was actually used. The castle itself (the whole structure, within the curtain wall) did, of course, have a military function as a secure base for a garrison and store although policing and administrative functions were the more regular aspect of the 'military' presence. The original timber castle is sometimes argued to have been nearby at Boley Hill
, although the earthworks there probably originated as a siege castle. The corner of the great tower undermined in the 1215 siege was replaced by a circular turret. This is normally suggested as being a specific design choice made for military reasons to lessen the risk of undermining. It should be noted this replacement is of poorer quality stone and shows much less skilled masonry work. It was a cheap repair and it may be the round form which, because of the lack of expenses ashlar corner quoins, was chosen as much for economic reasons as for any military concern.