▁dressed ▁stone work . ▁It ▁now ▁houses ▁the ▁Bibliothèque - Mus ée ▁de ▁l ' Op éra ▁de ▁Paris ▁( Par is ▁Opera ▁Library - M useum ) ▁which ▁is ▁home ▁to ▁nearly ▁ 6 0 0 , 0 0 0 ▁documents ▁including ▁ 1 0 0 , 0 0 0 ▁books , ▁ 1 , 6 8 0 ▁period ical s , ▁ 1 0 , 0 0 0 ▁programs , ▁letters , ▁ 1 0 0 , 0 0 0 ▁photograph s , ▁sketch es ▁of ▁cost umes ▁and ▁sets , ▁post ers ▁and ▁historical ▁administrative ▁records . ▁ ▁Pav illon ▁des ▁Ab onn és ▁Loc ated ▁on ▁the ▁right ▁( east ) ▁side ▁of ▁the ▁building ▁as ▁a ▁counter part ▁to ▁the ▁Pav illon ▁de ▁l ' Emp ere ur , ▁this ▁pav il ion ▁was ▁designed ▁to ▁allow ▁subscri bers ▁( ab onn és ) ▁direct ▁access ▁from ▁their ▁carri ages ▁to ▁the ▁interior ▁of ▁the ▁building . ▁ ▁It ▁is ▁covered ▁by ▁a ▁ 1 3 . 5 - met re ▁( 4 4 - ft ) ▁diameter ▁d ome . ▁Pa ired ▁ob el is ks ▁mark ▁the ▁ent ran ces ▁to ▁the ▁rot unda ▁on ▁the ▁north ▁and ▁the ▁south . ▁ ▁Inter ior ▁The ▁interior ▁consists ▁of ▁inter we aving ▁cor rid ors , ▁st air well s , ▁alc ov es ▁and ▁land ings , ▁allowing ▁the ▁movement ▁of ▁large ▁numbers ▁of ▁people ▁and ▁space ▁for ▁social ising ▁during ▁inter mission . ▁Rich ▁with