▁elev ated ▁to ▁have ▁potentially ▁fired ▁out ▁over ▁the ▁external ▁walls . ▁The ▁roof ▁has ▁the ▁remains ▁of ▁gun ▁positions ▁d ating ▁from ▁the ▁ 1 8 5 0 s , ▁and ▁was ▁originally ▁to pped ▁by ▁a ▁look - out ▁tower , ▁removed ▁in ▁ 1 8 0 5 . ▁When ▁first ▁built , ▁the ▁keep ▁was ▁linked ▁by ▁three ▁brid ges ▁to ▁the ▁outer ▁bast ions . ▁ ▁The ▁two - stor ied ▁north - west ▁bast ion ▁protected ▁the ▁castle ▁against ▁attack ▁along ▁the ▁sp it ▁from ▁the ▁main land , ▁and ▁hous ed ▁the ▁castle ' s ▁original ▁port c ull is ▁as ▁well ▁as ▁providing ▁accommod ation ▁for ▁the ▁g arrison . ▁It ▁had ▁three ▁levels ▁of ▁gun ▁positions ▁on ▁its ▁ground ▁floor , ▁first ▁floor ▁and ▁roof , ▁which ▁were ▁adapted ▁in ▁the ▁ 1 9 th ▁century ▁to ▁house ▁heav ier ▁weapons ▁and ▁shelter ▁rif le men . ▁The ▁bast ion ▁links ▁to ▁an ▁external ▁cap on ier , ▁a ▁covered ▁walk way ▁with ▁rif le ▁loops ▁for ▁close ▁defence , ▁built ▁in ▁ 1 8 5 2 . ▁The ▁north - east ▁and ▁south - east ▁bast ions ▁are ▁only ▁one ▁store y ▁tall , ▁originally ▁holding ▁two ▁levels ▁of ▁gun ▁positions ▁on ▁the ▁ground ▁floor ▁and ▁roof s , ▁again ▁both ▁adapted ▁to ▁support ▁heav ier ▁guns ▁in ▁the ▁ 1 9 th ▁century . ▁ ▁West ▁and ▁East ▁W ings ▁▁ ▁The ▁West ▁and ▁East ▁Wing ▁date ▁from ▁the ▁ 1 8 6