That was one of the most interesting cities I've visited. The city was a mix of medieval architecture and pieces of a Roman palace. There were the brick walls of buildings built between Roman columns and there was a Roman-era mausoleum on one side of the street. It was clear that it used to be quite an open layout that was filled in by buildings in later centuries.
It must have been interesting in the early days of the city with a bunch of people occupying an old palace, fortifying it, and building houses for themselves within the grounds.
I wondered what Diocletian would have thought to see his old palace transformed in such a way.
https://en.wikipedia.org/wiki/Split,_Croatia
Maybe Edinburgh and volcanoes as well...
https://en.wikipedia.org/wiki/Edinburgh_Castle#Geology