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 to Petrograd in 1924 to Leningrad and in 1991 back to Saint Petersburg.
The area of Saint Petersburg city proper is 605.8 square kilometers (233.9 sq mi). The area of the federal subject is 1,439 square kilometers (556 sq mi), which contains Saint Petersburg proper (consisting of eighty-one municipal okrugs), nine municipal towns – (Kolpino, Krasnoye Selo,Kronstadt, Lomonosov, Pavlovsk, Petergof, Pushkin,Sestroretsk, Zelenogorsk) – and twenty-one municipal settlements.
Petersburg is situated 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.
The elevation of Saint Petersburg ranges from the sea level to its highest point of 175.9 meters (577 ft) at the Orekhovaya Hill in the Duderhof Heights in the south. Part of the city's territory west of Liteyny Prospekt is no higher than 4 meters (13 ft) above sea level, and has suffered from numerous floods. Floods in Saint Petersburg are triggered by a long wave in the Baltic Sea, caused by meteorological conditions, winds and shallowness of the Neva Bay. The four most disastrous floods occurred in 1824 (421 centimeters / 166 inches above sea level, during which over three hundred buildings were destroyed), 1924 380 centimeters / 150 inches, 1777 321 centimeters / 126 inches, 1955 293 centimeters / 115 inches, and 1975 281 centimeters / 111 inches. To prevent floods, the Saint Petersburg Dam has been