 The cathedral faces south and is approximately 54 @.@ 5 metres ( 179 ft ) wide and 110 metres ( 360 ft ) long . It consists of two bell towers , a central dome , three main portals , five naves , 51 vaults , 74 arches and 40 columns . Inside the cathedral are five large altars , sixteen chapels , a choir area , a corridor , <unk> room , and sacristy . The cathedral has approximately 150 windows . 
