Limes in Weißenburg (Roman garrison fortification). The length of this ancient Roman frontier on the site of former fortresses, watchtowers, estates and thermal spas the secrets locked away underground have been revealed through archaeological digs.
Steinhuder Meer. This lake in Lower Saxony, about an hour outside Hanover, is the largest in northwestern Germany. It's quite shallow, though, making it a good destination for families with small children.