Saint Petersburg, formerly known as Nyenschantz (Ниеншанц) and after that Petrograd (Петроград) and later Leningrad (Ленинград), is the second-largest city in Russia, after Moscow, the nation's capital. Situated on the Neva River at the head of the Gulf of Finland on the Baltic Sea, its area of 1,439 square kilometers (556 sq mi) renders it the smallest administrative division of Russia by area. The city had a population of 5,601,911 residents as of 2021, with more than 6.4 million people living in the metropolitan area.