Favorite thing: Split's Old Town and the Diocletian's Palace are full of interesting sights, including this impressive six storey campanile that rises above the Cathedral of St. Domnius in the heart of the palace. It was begun in the 13th century, but wasn't finally completed until 1908. The views from the top are great. You'll be able to get your bearings in the palace and see well beyond the Old Town out to greater Split.
The Cathedral inside Diocletian's Palace is actually one of the smallest in the world, but none of the less a very interesting one.
The Bell Tower was built in the narrow space between the Cathedral and the Peristyle in the 13th to 14th century, in a romanesque style, with the gothic-rennaissance end on top. During the reconstruction in the 19th century the bell-tower was radically transformed, and many of the original romanesque sculptures were removed.
One very interesting fact is that The Cathedral bears the St.Maria's name and only the Bell Tower bears the name of St.Doimus (Sveti Dujam) - the bishop of Salona.
Both the civil and the religious heritage of the ancient Salona have been particularly important for the historical development of Split since the very beginning. The refugees from the conquered and devastated Salona fled from their native town to take shelter behind the mighty walls of the imperial Palace, where the organization of urban life started to develop since 7th century. They had worshipped their martyr saints at Salona, so they transferred their relics to the new site, upon their arrival. One of those martyrs, St. Domnio, was chosen to be the patron saint of the city of Split. The cult of the Virgin Mary, once worshipped at Salona, has been followed here, in a new place of residence, therefore, the local cathedral, previously Diocletian's Mausoleum, was consecrated to Virgin Mary very early, probably in 7th century.
In the early Middle Ages, the organization and the management of each city, and its autonomy were mainly based on religious heritage. The Church of Split, owing to the religious heritage of the Salona diocese and its rights, was promoted into an Archdiocese during the synods that took place in Split in 925 and 928 A.D. The Archbishop was John, a son of Tordakat (Tvrtko?), born, brought up and educated in Split, whose sarcophagus with carved inscription is still preserved.
The portal of St. Domnio's cathedral is decorated by the wooden doors, carved by Andrija Buvina in 1215. Inside the Cathedral there are the Romanesque pulpit, a valuable late Gothic sculpture by A.Aleši and an Early-Renaissance sculpture by George the Dalmatian, as well as many other valuable Baroque paintings. Close to the Cathedral there is the Cathedral Treasury where many relics, religious books, liturgical garments and other objects have been displayed.