Meersburg, on the Bodensee
Bacharach-Rheingau
Random castles
Seriously. There are random castles all over the place. Drive on the autobahn to someplace and I guarantee you will pass by at least one castle on a hill before your destination.
It just illustrates how important Germany in general has been over the years and also how difficult it was to hold various spots; each castle, however close-seeming, protected a specific kingdom.