The Cathedral of Saint Domnius is one of the oldest Catholic cathedrals in the world still in active use. Built within the Roman Emperor Diocletian's mausoleum constructed around 305 AD, it was consecrated as a church in the 7th century. The 57-meter bell tower offers breathtaking panoramic views over Split, the islands, and Marjan Hill. The interior houses original Roman sculptures, relief carvings, and the cathedral treasury. The crypt contains the relics of Saint Domnius, the city's patron saint. The cathedral offers color-coded tickets covering different combinations of sites at prices ranging from EUR 7 to 15, including the cathedral itself, bell tower, crypt, baptistery, and treasury