Dear friend: The most famous castles in Germany and France are not medieval. Loira river castles were built in the Renaissance (XVIth century) and other castles even in the XIXth (Neuschwanstein). Of course there are medieval castles. But if you want to see a real lot of medieval castles i guess you must go to the Spanish region of Castilia (named so due to its castles). Maybe they are less impressive than the biggest French castles, but here you have much more. Just in north Castilia, 579 castles. My favorite is Coca's Castle. Spain has also one of the most beautiful fortress ever, Alhambra, in Granada. Hope you like your trip!