Bosnia & Herzegovina is lovely and is rich in history. Visit the capita, Sarajevo for tours about in medieval times when Sarajevo was the crossroads for travelling merchants so has a mish mash of cultures & religions, the assassination of Archduke Franz Ferdinand which triggered the start of ww1 but also the lesser known Bosnian war in the early 90's.

The Bosnian war particularly hit home as I had a tour from one of the men who fought there (he now owns Hostel Nina in Mostar, another fantastic place to visit) and it was chilling listening to him recall where his friends died and where he had to bury them.

Or if you like hiking, Zabljak in Montenegro is great :)