I found a link to a place called Virtual Tourist. It is a little difficult to navigate, but essentially is people who like to travel or live in a place posting about it. There I found this link to an article about Diocletian's Palace in Split, Coratia, which will tell you who Diocletian was. Also a walking tour here.
Although it is one of the most important monuments from the late antiquity and the best preserved Roman palace – when you arrive to Split, you won’t have to pay for the entrance to see it. That’s because it is still the center of Split, the area which is referred to as “Grad” - “The Town”.
I have also seen recommendations to go on the tours to the countryside, to Trogir, along the Dalmatian coast. All very exotic sounding. Maybe this is the place to do a ship tour!
