Roman emperor Diocletian is perhaps the most notable resident of Split, Croatia’s second most-populated city. What used to be his palace now constitutes almost the entirety of the modern city’s UNESCO-protected historic center. His life story in some ways reflects the twin cities found on this Croatian peninsula: Solin and Spalato. Diocletian was born in Salona, now known as Solin, and is considered a town within Split’s metropolitan area. Yet it was Spalato (now Split proper) where he decided to build the palace he would retire to following his abdication…