The Cathedral of St. Duje is the Catholic cathedral of Split, the largest Dalmatian city and the seat of Split-Dalmatia County, in Croatia. The cathedral is the seat of the Archdiocese of Split-Makarska, headed by Archbishop Marin Barišić. The Cathedral of St (...) (from Wikipedia).
Ironically built as a mausoleum for an emperor with a penchant for having Christians thrown to the lions this grand building now houses the city's cathedral. Look out for the 13th-century wooden door that depicts the life of Christ as well as a portrait of Diocletian's wife Prisca.
Address: Kraj Svetog Duje.