Budapest is the capital and most populous city of Hungary. It is the tenth-largest city in the European Union by population within city limits and …Budapest is the capital and most populous city of Hungary. It is the tenth-largest city in the European Union by population within city limits and the second-largest city on the river Danube. The estimated population of the city in 2025 is 1,782,240. This includes the city's population and surrounding suburban areas, according to worldpopulationreview.com. over a land area of about 525 square kilometres. 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. It is a primate city, constituting 33% of the population of Hungary.