▁of ▁maintenance . ▁Due ▁to ▁the ▁decay ed ▁state ▁of ▁the ▁keep , ▁public ▁access ▁is ▁restricted ▁and ▁net ting ▁has ▁been ▁ere cted ▁to ▁protect ▁visitors . ▁The ▁possibility ▁of ▁adding ▁flo ors ▁and ▁a ▁roof ▁to ▁the ▁keep ▁was ▁discussed ▁in ▁the ▁ 1 9 7 0 s ▁and ▁ 1 9 9 0 s , ▁but ▁there ▁were ▁concerns ▁that ▁a ▁roof ▁would ▁change ▁the ▁climate ▁within ▁the ▁building . ▁The ▁castle ▁is ▁a ▁Sch eduled ▁Monument , ▁a ▁" n ation ally ▁important " ▁historic ▁building ▁and ▁arch ae ological ▁site ▁which ▁has ▁been ▁given ▁protection ▁against ▁una ut hor ised ▁change . ▁It ▁is ▁also ▁a ▁Gra de   I ▁listed ▁building , ▁and ▁recogn ised ▁as ▁an ▁intern ation ally ▁important ▁structure . ▁The ▁castle ▁is ▁open ▁to ▁the ▁public . ▁ ▁Architecture ▁ ▁Little ▁is ▁known ▁about ▁the ▁design ▁of ▁the ▁first ▁castle ▁at ▁Ro chester ▁as ▁it ▁has ▁since ▁van ished , ▁and ▁even ▁the ▁exact ▁site ▁is ▁uncertain . ▁It ▁most ▁likely ▁took ▁the ▁form ▁of ▁a ▁mot te - and - ba iley ▁castle , ▁with ▁a ▁m ound ▁and ▁an ▁outer ▁en closure ▁def ended ▁by ▁a ▁tim ber ▁pal is ade ▁and ▁ear then ▁banks . ▁B ole y ▁Hill ▁has ▁been ▁suggested ▁as ▁the ▁site ▁of ▁the ▁first ▁castle , ▁an ▁out work ▁rein for cing ▁the ▁castle ' s ▁def ences , ▁or ▁an ▁abandoned ▁sie ge ▁castle ▁like ▁those ▁documented ▁in ▁the ▁ 1 0 8 8 ▁sie