Berlin is the capital and largest city of Germany by both area and population. Its more than 3.85 million inhabitants make it the European Union's most populous city, according to population within city limits. The greater urban area of Berlin is one of the States of Germany. Berlin is surrounded by the State of Brandenburg and Brandenburg's capital Potsdam is nearby. Berlin's urban area has a population of around 4.5 million and is therefore the most populous urban area in Germany. The Berlin-Brandenburg capital region has around 6.2 million inhabitants and is Germany's second-largest metropolitan region after the Rhine-Ruhr region and the sixth biggest Metropolitan Region by GDP in the European Union.