In the valley of the Regnitz where the river divides into two arms, Bamberg, the old imperial city and the most important town in Upper Franconia, is one of the best preserved of Germany's many charming old towns. Its old episcopal quarter is home to the 13th-century cathedral and the old Benedictine abbey of Michaelsberg. It's between the two river branches that you'll find spectacular Bürgerstadt, a small borough of Bamberg that contains the Grüner Markt,