Mannheim

Mannheim needs 1 day: Mannheim Palace -one of Europe's largest Baroque palaces, now part of the university- and the city's grid layout unique in Germany (divided into blocks identified by letters and numbers instead of street names) on the same walk. April-September has the best weather. It's cheaper than Heidelberg, just 20 minutes away by train. It's considered the birthplace of the automobile -Karl Benz patented the first combustion-engine car here in 1886- and of the modern bicycle, with a 17th-century Baroque grid layout unmatched by any other German city.