Die Landeshauptstadt von Nordrhein-Westfalen heißt …The capital city of North Rhine-Westphalia is called...

Explanation

Düsseldorf is designated as the capital in §3 of the NRW Landesorganisationsgesetz. It houses the state parliament, the State Chancellery, and most ministries, whereas Cologne, Bonn, and Dortmund are important cities but not the seat of government.