Substructure of Diocletian's Palace, Split.

Covering a vast underground network, the substructure of Diocletian's Palace in Split was for me the most impressive part of the Old City. What I found most suprising was how much the surface world intrudes below. Music from above-ground bars and resturants filters through grills and doorways. Sunlight streams in from open areas of ceiling.

It's also still in regular use, with installation art taking place in small side rooms, which was a nice find.