Diocletian's palace and Dubrovnik's Old Town have interesting architecture, as well.
I travel solo almost all the time now and love it; my most recent trip was Slovenia and Croatia and I highly recommend both. The beaches in Croatia are gorgeous and the scenery in both countries is amazing. Full of history, too. Diocletian's palace and Dubrovnik's Old Town have interesting architecture, as well. Both are very safe for solo females.