 The cathedral went through periods of enlargement and renovation following the fires of 1270 and 1390 that included the doubling in length of the choir , the provision of outer aisles to the northern and southern walls of both the nave and choir . Today , these walls are at full height in places and at foundation level in others yet the overall cruciform shape is still discernible . A mostly intact octagonal chapter house dates from the major enlargement after the fire of 1270 . The gable wall above the double door entrance that links the west towers is nearly complete and was rebuilt following the fire of 1390 . It accommodates a large window opening that now only contains <unk> tracery work and fragments of a large rose window . <unk> and chest tombs in both transepts and in the south aisle of the choir contain effigies of bishops and knights , and large flat slabs in the now grass @-@ covered floor of the cathedral mark the positions of early graves . The homes of the dignitaries and canons , or manses , stood in the chanonry and were destroyed by fire on three occasions : in 1270 , 1390 and 1402 . The two towers of the west front are mostly complete and were part of the first phase of construction . Only the precentor 's manse is substantially intact ; two others have been incorporated into private buildings . A protective wall of massive proportions surrounded the cathedral precinct , but only a small section has survived . The wall had four access gates , one of which — the <unk> Port — still exists . 
