Split is an ancient city founded on the Adriatic coast toward the end of the 3rd century. It is here that the emperor Diocletian built his walled castle on the slopes above the bay. Today that well-preserved palace and the later historic building built within its walls, form the heart of old Split, earning the community a place on the UNESCO list of World Heritage Sites. Split is a busy port with numerous ferries operating to and from nearby islands. It is also a popular resort with beaches and pleasant promenades.