Best places to visit in Mannheim

Mannheim (German pronunciation: [ˈmanhaɪm]; Palatine German: Monnem or Mannem) is a city in the southwestern part of Germany, the third-largest in the German state of Baden-Württemberg after Stuttgart and Karlsruhe with a 2015 population of approximately 305,000 inhabitants.
It's 08:52 right now , with overcast clouds and the temperature of 1.73°C (35.114°F) in Mannheim.