Budapest is the capital and most populous city of Hungary. With a population of 1,686,222 spread over about 525 square kilometres, it is the tenth-largest city in the European Union by population within city limits and the second-largest city on the river Danube. Budapest, which is both a city and municipality, forms the centre of the Budapest metropolitan area, which has an area of 7,626 square kilometres and a population of 3,019,479. Because this metropolitan area contains 33% of the population of Hungary, Budapest is considered a primate city.