Düsseldorf is the capital city of North Rhine-Westphalia, the most populous state in Germany. Situated primarily on the right bank of the Rhine River, it serves as a central hub within the Rhine-Ruhr metropolitan region, which is the second-largest by GDP in the European Union. The city lies near the mouth of the Düssel River and has grown to merge with neighboring municipalities such as Neuss, Krefeld, and Ratingen.