▁remains ▁significantly ▁int act ▁and ▁is ▁considered ▁one ▁of ▁the ▁most ▁important ▁surv iving ▁ 1 2 th - century ▁keeps ▁in ▁England ▁and ▁France . ▁The ▁keep ▁was ▁rich ly ▁decor ated ▁with ▁hang ings ▁and ▁furn ish ings . ▁D ating ▁from ▁the ▁second ▁quarter ▁of ▁the ▁ 1 2 th ▁century , ▁it ▁is ▁Ro chester ▁Castle ' s ▁dominant ▁feature . ▁It ▁had ▁a ▁square ▁plan , ▁and ▁measures ▁ ▁extern ally ▁with ▁pil aster ▁but tr esses ▁at ▁each ▁corner . ▁The ▁keep ▁was ▁built ▁in ▁the ▁castle ' s ▁southern ▁corner , ▁close ▁to ▁the ▁cur tain ▁wall . ▁The ▁primary ▁building ▁material ▁was ▁local ▁Kent ish ▁R ag stone ; ▁Ca en ▁stone ▁used ▁to ▁face ▁the ▁keep ▁was ▁imported ▁from ▁Norm andy . ▁The ▁same ▁material ▁was ▁imported ▁for ▁the ▁Tower ▁of ▁London ' s ▁White ▁Tower ▁in ▁the ▁ 1 1 th ▁century . ▁The ▁to ps ▁of ▁the ▁tur rets ▁rise ▁ ▁above ▁the ▁ground , ▁ 1 2   ft ▁above ▁the ▁batt lement s . ▁Below ▁the ▁latter ▁are ▁rect angular ▁holes , ▁mark ing ▁where ▁wooden ▁ho arding ▁would ▁have ▁been ▁attached . ▁The ▁walls ▁of ▁the ▁keep ▁are ▁ 1 2   ft ▁thick ▁at ▁the ▁base , ▁and ▁t aper ▁to ▁ 1 0   ft ▁at ▁the ▁top . ▁It ▁is ▁the ▁tall est ▁keep ▁in ▁England , ▁and ▁only ▁those ▁at ▁D over , ▁the ▁Tower ▁of ▁London , ▁Col chester , ▁and ▁Nor wich ▁are