Saint Petersburg, formerly known as Petrograd (19141924) and later Leningrad (19241991), is the second-largest city in Russia after Moscow.   It is situated on the Neva River, at the head of the Gulf of Finland on the Baltic Sea.   Saint Petersburg is the fourth-most populous city in Europe, the most populous city on the Baltic Sea, and the world's northernmost city of more than 1 million residents.   As Russia's Imperial capital, and a historically strategic port, it is governed as a federal city.

The city was founded by Tsar Peter the Great on 27 May 1703 on the site of a captured Swedish fortress, and was named after apostle Saint Peter.   In Russia, Saint Petersburg is historically and culturally associated with the birth of the Russian Empire and Russia's entry into modern history as a European great power.   It served as a capital of the Tsardom of Russia, and the subsequent Russian Empire, from 1713 to 1918 (being replaced by Moscow for a short period of time between 1728 and 1730).   After the October Revolution in 1917, the Bolsheviks moved their government to Moscow. The city was renamed Leningrad after Lenin's death in 1924.   In 1991, during a wave of De-Leninization following the dissolution of the USSR, the city was restored to its original appellation through a city-wide referendum.

As Russia's cultural centre, Saint Petersburg received over 15 million tourists in 2018.   It is considered an important economic, scientific, and tourism centre of Russia and Europe. In modern times, the city has the nickname of being "the Northern Capital of Russia" and is home to notable federal government bodies such as the Constitutional Court of Russia and the Heraldic Council of the President of the Russian Federation.   It is also a seat for the National Library of Russia and a planned location for the Supreme Court of Russia, as well as the home to the headquarters of the Russian Navy, and the Western Military District of the Russian Armed Forces.   The Historic Centre of Saint Petersburg and Related Groups of Monuments constitute a UNESCO World Heritage Site.   Saint Petersburg is home to the Hermitage, one of the largest art museums in the world, the Lakhta Center, the tallest skyscraper in Europe.

Petersburg is on the middle taiga lowlands along the shores of the Neva Bay of the Gulf of Finland, and islands of the river delta.   The largest are Vasilyevsky Island (besides the artificial island between Obvodny canal and Fontanka, and Kotlin in the Neva Bay), Petrogradsky, Dekabristov and Krestovsky.   The latter together with Yelagin and Kamenny Island are covered mostly by parks.   The Karelian Isthmus, North of the city, is a popular resort area.   In the south, Saint Petersburg crosses the Baltic-Ladoga Klint and meets the Izhora Plateau.   Due to its northerly location at 60 N latitude the day length in Petersburg varies across seasons, ranging from 5 hours 53 minutes to 18 hours 50 minutes.   A period from mid-May to mid-July during which twilight may last all night is called the white nights.   Saint Petersburg is home to many parks and gardens.   Some of the most well-known are in the southern suburbs, including Pavlovsk, one of Europe's largest English garden.   Sosnovka is the largest park within the city limits. Saint Petersburg has a significant historical and cultural heritage.

The city's 18th and 19th-century architectural ensemble and its environs is preserved in virtually unchanged form.   Saint Petersburg's loss of capital city status helped it retain many of its pre-revolutionary buildings, as modern architectural 'prestige projects' tended to be built in Moscow; this largely prevented the rise of mid-to-late-20th century architecture and helped maintain the architectural appearance of the historic city centre.   The city has 221 museums, 2,000 libraries, more than 80 theatres, 100 concert organizations, 45 galleries and exhibition halls, 62 cinemas, and 80 other cultural establishments.   Every year the city hosts around 100 festivals and various competitions of art and culture, including more than 50 international ones.   Saint Petersburg is a major transport hub.   The first Russian railway was built here in 1837, and since then the city's transport infrastructure has kept pace with the city's growth.