Saint-Petersburg (Russian: Санкт-Петербург, tr. Sankt-Peterburg; IPA: [ˈsankt pʲɪtʲɪrˈburk] ( listen)) is the second largest city in Russia, politically incorporated as a federal subject (a federal city). It is located on the Neva River at the head of the Gulf of Finland on the Baltic Sea. In 1914 the name of the city was changed from Saint Petersburg to Petrograd (Russian: Петроград; IPA: [pʲɪtrɐˈgrat]), in 1924 to Leningrad (Russian: Ленинград; IPA: [lʲɪnʲɪnˈgrat]), and in 1991, back to Saint-Petersburg.

In Russian literature, informal documents, and discourse, the word "Saint" (Russian: Санкт) is usually omitted, leaving "Petersburg" (Russian: Петербург). In casual conversation Russians may drop the "burg" (Russian: бург) as well, referring to it as "Piter" (Russian: Питер).

Saint-Petersburg was founded by Tsar Peter the Great on May 27 [O.S. 16] 1703. Between 1713–1728 and 1732–1918, Saint Petersburg was the imperial capital of Russia. In 1918, the central government bodies moved from Saint Petersburg (then named Petrograd) to Moscow. It is Russia's 2nd largest city after Moscow with 5 million inhabitants (2012) and the fourth most populated federal subject. Saint-Petersburg is a major European cultural center, and also an important Russian port on the Baltic Sea.

Saint-Petersburg is often described as the most Westernized city of Russia, as well as its cultural capital. It is the northernmost city in the world with a population of over one million. The Historic Centre of Saint-Petersburg and Related Groups of Monuments constitute a UNESCO World Heritage Site. Saint Petersburg is also home to The Hermitage, one of the largest art museums in the world. A large number of foreign consulates, international corporations, banks, and other businesses are located in Saint-Petersburg.