Germany is a federal parliamentary republic in central-western Europe. It includes 16 constituent states, covers an area of 357,021 square kilometres (137,847 sq mi), and has a largely temperate seasonal climate. With about 82 million inhabitants, Germany is the most populous member state of the European Union. After the United States, it is the second most popular immigration destination in the world. Germany's capital and largest metropolis is Berlin, while its largest conurbation is the Ruhr (main centres: Dortmund and Essen). Other major cities include Hamburg, Munich, Cologne, Frankfurt, Bremen, Stuttgart, Düsseldorf and Leipzig.