1a city and seaport in northwestern Russia, located on the delta of the Neva River, on the eastern shores of the Gulf of Finland; population 4,548,000 (est. 2008). Founded in 1703 by Peter the Great, St. Petersburg was the capital of Russia from 1712 until the Russian Revolution. During World War II, it was held under siege by the Germans and Finns 1941–44. Former names Petrograd (1914–24) and Leningrad (1924–91). 2a resort city in western Florida, on the Gulf of Mexico; population 245,314 (est. 2008).