Heidelberg's Old Town is one of Germany's most enchanting historic city centers, stretching along the Neckar River between the Old Bridge and the castle. The Hauptstraße is Germany's longest pedestrian street at over 1.6 km, lined with shops, restaurants, and baroque buildings. The Old Town largely survived World War II destruction, preserving authentic 17th and 18th-century architecture. Highlights include the Marktplatz with Hercules Fountain, the Church of the Holy Spirit, Germany's oldest university, and numerous charming squares.