▁doors ▁( 1 1 1 9 ▁and ▁ 1 1 2 4 ); ▁Rav ello ▁( 1 1 7 9 ), ▁by ▁Bar is ano ▁of ▁T ran i , ▁who ▁also ▁made ▁doors ▁for ▁T ran i ▁c athedral ; ▁and ▁in ▁Mon re ale ▁and ▁P isa ▁c athed r als , ▁by ▁Bon ano ▁of ▁P isa . ▁In ▁all ▁these ▁cases ▁the ▁h anging ▁st ile ▁had ▁p iv ots ▁at ▁the ▁top ▁and ▁bottom . ▁The ▁exact ▁period ▁when ▁the ▁h inge ▁was ▁subst it uted ▁is ▁not ▁quite ▁known , ▁but ▁the ▁change ▁apparently ▁brought ▁about ▁another ▁method ▁of ▁strength ening ▁and ▁decor ating ▁doors , ▁viz , ▁with ▁wr ought - ir on ▁bands ▁of ▁infinite ▁vari eties ▁of ▁design . ▁As ▁a ▁rule ▁three ▁bands ▁from ▁which ▁the ▁orn amental ▁work ▁spr ings ▁const itute ▁the ▁h ing es , ▁which ▁have ▁rings ▁outside ▁the ▁h anging ▁st iles ▁fitting ▁on ▁to ▁vertical ▁ten ons ▁run ▁into ▁the ▁m ason ry ▁or ▁wooden ▁frame . ▁There ▁is ▁an ▁early ▁example ▁of ▁the ▁ 1 2 th ▁century ▁in ▁Lincoln ; ▁in ▁France ▁the ▁metal ▁work ▁of ▁the ▁doors ▁of ▁Notre ▁D ame ▁at ▁Paris ▁is ▁perhaps ▁the ▁most ▁beautiful ▁in ▁execution , ▁but ▁examples ▁are ▁end less ▁throughout ▁France ▁and ▁England . ▁ ▁Return ing ▁to ▁Italy , ▁the ▁most ▁celebrated ▁doors ▁are ▁those ▁of ▁the ▁Batt ister o ▁di ▁San ▁Giovanni ▁( F lor ence ), ▁which ▁together ▁with ▁the ▁door ▁frames ▁are ▁all