Mannheim, officially the University City of Mannheim, is the second-largest city in Baden-Württemberg after Stuttgart, the state capital, and Ger…Mannheim, officially the University City of Mannheim, is the second-largest city in Baden-Württemberg after Stuttgart, the state capital, and Germany's 21st-largest city, with a population of around 317,000. The city is the cultural and economic centre of the Rhine-Neckar, Germany's seventh-largest metropolitan region, with nearly 2.4 million inhabitants.