▁of ▁western ▁wall ▁are ▁the ▁remains ▁of ▁a ▁building , ▁probably ▁a ▁hall , ▁d ating ▁from ▁the ▁ 1 3 th   century . ▁Its ▁v ault ed ▁under cro ft ▁is ▁no ▁longer ▁standing . ▁ ▁In ▁the ▁south ▁G und ulf ' s ▁wall ▁surv ived ▁into ▁the ▁modern ▁period , ▁but ▁has ▁now ▁been ▁dis m ant led . ▁The ▁current ▁wall ▁is ▁a ▁ 1 9 th - century ▁replacement . ▁At ▁the ▁eastern ▁end ▁of ▁this ▁wall , ▁near ▁the ▁southern ▁corner ▁of ▁the ▁castle , ▁is ▁a ▁two - store y ▁rounded ▁tower ▁ ▁in ▁diameter ▁d ating ▁from ▁the ▁early ▁ 1 3 th   century . ▁It ▁was ▁built ▁to ▁fill ▁the ▁bre ach ▁in ▁the ▁cur tain ▁wall ▁caused ▁when ▁John ' s ▁army ▁bes ie ged ▁the ▁castle ▁and ▁to ▁rein force ▁a ▁weak ▁point ▁in ▁the ▁def ences . ▁The ▁section ▁from ▁the ▁tower ▁to ▁the ▁location ▁of ▁the ▁former ▁main ▁gate house ▁in ▁the ▁north - east ▁dates ▁from ▁about ▁ 1 3 6 7 ▁to ▁ 1 3 7 0 . ▁Two ▁to wers ▁were ▁built ▁along ▁the ▁wall , ▁each ▁two ▁store ys ▁high ▁and ▁again ▁using ▁Kent ish ▁R ag stone . ▁The ▁one ▁nearest ▁the ▁keep ▁is ▁relatively ▁plain ▁and ▁the ▁northern most ▁one ▁more ▁elaborate . ▁The ▁latter ▁was ▁intended ▁for ▁use ▁as ▁a ▁residence ▁and ▁in ▁the ▁modern ▁period ▁was ▁converted ▁into ▁a ▁c ott age . ▁The ▁wall ▁between ▁these ▁two ▁to wers