Berlin is the capital city of Germany and one of the 16 states of Germany. With a population of 3.4 million people, Berlin is the second most populous city proper and the seventh most populous urban area in the European Union, and is Germany's largest city. Located in northeastern Germany on the River Spree, it is the center of the Berlin-Brandenburg Metropolitan Region, which has about 4.5 million residents from over 180 nations. Due to its location in the European Plain, Berlin is influenced by a temperate seasonal climate. Around one third of the city's area is composed of forests, parks, gardens, rivers and lakes.