Kunsthalle Museum Mannheim

Mannheim's premier gallery is a vast repository of modern and contemporary art by masters such as Cézanne, Degas, Manet, Kandinsky and Rodin. The permanent collection has often been stored away to make space for blockbuster exhibitions, but that will change with the opening of a new €70 million metal-encased, glass-roofed, 16,000-sq-metre exhibition space. It's due to open in late 2018; check with the tourist office for updates.