On an island in the gentle little Kinzig River you'll find the remains of the Kaiserpfalz. Emperor Friedrich I—known as Barbarossa, or Red Beard—built the castle in this idyllic spot in the 12th century; in 1180 it was the scene of the first all-German Imperial Diet, a gathering of princes and ecclesiastical leaders. Today only parts of the russet walls and colonnaded entrance remain. Still, you can stroll beneath the castle's ruined ramparts on its water site and you'll get a tangible impression of the medieval importance of the court of Barbarossa.
Burgstr. 14, Gelnhausen, 63571, Germany