Ludwigshafen, Germany

Ludwigshafen am Rhein is a grid-planned industrial city on the Rhine whose skyline is dominated by the sprawling BASF chemical complex, the world’s largest integrated chemical site. Though its 176,000 residents live with the hum of industry, art lovers come for the modern Wilhelm-Hack Museum and its blazing stained-glass “Blue Wall,” while riverfront parks and the 19th-century Eberthalle offer surprising green and cultural respites amid the smokestacks.