The ninth edition of the four-day event was opened by Mayor Ivo Baldasar dressed in a white toga, as worn in Emperor Diocletian's time 1,700 years ago. He hoped the event would bring more tourists to Split.
The emperor, played by actor Goran Nikolic, thanked the mayor for letting him rule the city over the next four days. Empress Priska is played by athletes and sisters Ana and Lucija Zaninovic.
Tourism minister advisor Ivo Basic, also dressed in a white toga, said Days of Diocletian should be promoted more to become a "serious tourist attraction."
Before the opening, the emperor and the empress drove around Split in a horse-drawn carriage. The opening was followed by a gladiator fight in which Diocletian's soldiers took part, while those in attendance were entertained by his dancers.
A dinner was organised as well, with food that Split's residents used to eat 17 centuries ago.
Days of Diocletian include numerous music events reminiscent of the emperor's era, a fair, street performances, gladiator fights and concerts.