Warsaw, officially the Capital City of Warsaw, is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland and its population is officially estimated at 1.8 million residents within a greater metropolitan area of 3.1 million residents, which makes Warsaw the 7th most-populous capital city in the European Union. The city area measures 517 km2 (200 sq mi) and comprises 18 boroughs, while the metropolitan area covers 6,100 km2 (2,355 sq mi). Warsaw is an alpha− global city, a major cultural, political and economic hub, and the country's seat of government. Its historical Old Town was designated a UNESCO World Heritage Site.