In what city or state did the formation of XXX occur?
Diocletian's Palace
Diocletian's Palace (Croatian: Dioklecijanova palača, pronounced (diɔklɛt͡sijǎːnɔʋa pǎlat͡ʃa)) is an ancient palace built by the Roman emperor Diocletian at the turn of the fourth century AD, that today forms about half the old town and city center of Split, in Croatia.
Split