Saint Petersburg ( , tr.: Sankt-Peterburg, sankt pʲɪtʲɪrˈburk) is a city and a federal subject of Russia located on the Neva River at the east end of the Gulf of Finland on the Baltic Sea. St. Petersburg's informal name, Piter (Пи́тер), is based on how Peter the Great was called by foreigners. The city's other names were Petrograd (Петрогра́д, 1914–1924) and Leningrad (Ленингра́д, 1924–1991).

Founded by Tsar Peter the Great on May 27, 1703, it was the capital of the Russian Empire for more than two hundred years (1713-1728, 1732-1918). St. Petersburg ceased being the capital in 1918 after the Russian Revolution of 1917. It is Russia's second largest and Europe's fourth largest city (by city limit) after Moscow, London and Paris. At latitude 59°56′N, Saint Petersburg is the world's largest city north of Moscow (55°45′N). 4.6 million people live in the city, and over 6 million people live in the city's vicinity. Saint Petersburg is a major European cultural center, and important Russian port on the Baltic Sea. The city, as federal subject, has a total area of .

St. Petersburg has the image of being the most Western European styled city of Russia. Among cities of the world with over one million people, Saint Petersburg is the northernmost. The Historic Centre of Saint Petersburg and Related Groups of Monuments constitute a UNESCO World Heritage Site. Russia's political and cultural center for 200 years, the city is impressive, and is sometimes referred to in Russia as "the Northern Capital" (северная столица, severnaya stolitsa).