Cologne is the largest city of the German state of North Rhine-Westphalia and the fourth-most populous city of Germany with nearly 1.1 million inhabitants in the city proper and over 3.1 million people in the Cologne Bonn urban region. Cologne is also part of the Rhine-Ruhr metropolitan region, the second biggest metropolitan region by GDP in the European Union. Centered on the left (west) bank of the Rhine, Cologne is about 35 km (22 mi) southeast of the North Rhine-Westphalia state capital Düsseldorf and 25 km (16 mi) northwest of Bonn, the former capital of West Germany.