Americans have long been drawn to the charms of Munich and, more recently, the energy of Berlin. But right now, arguably, the most exciting metropolis in Germany is Hamburg. One of the continent’s wealthiest cities and for centuries one of its most important ports, Hamburg nevertheless has a reputation for reserve, not excitement. Perhaps its instinct for restraint has something to do with the fact that the city is closer, both culturally and geographically, to Scandinavia than southern Germany. Its ties to the great cities of the North and Baltic seas go back at least to the Middle Ages, when Hamburg ranked among the most important members of the Hanseatic League and Bavaria was another country entirely.