Regensburg, Germany

Regensburg sits on the Danube in Bavaria with about 155,000 residents. The 1135 Stone Bridge, spanning 310 meters, was the strongest medieval bridge in Europe and the model for Prague's Charles Bridge. The 1273 Saint Peter's Cathedral, with spires of roughly 85 meters, is the largest Gothic church in Bavaria. The Imperial Diet met here some 200 times beginning in 1245, making the city the de facto capital of the Holy Roman Empire for around 150 years, while its UNESCO-listed medieval centre holds about 1,500 listed buildings. The 1663 Perpetual Diet sat here until 1806, and the 1623 Wurstkuchl ranks as Germany's oldest continuously open restaurant.