Scientists proved that water level in the Neva river may raise to 5.4 meters. In such a case 30% of city territory would be flooded up to a conditional border on Lesnoy and Liteiny prospects including Petrograd side, Vasilevsky Island, Central, Admiralteisky, Kirovsky, Primorsky and Moscow districts. The Summer Garden, the Field of Mars, the Hermitage and the subway would appear underwater. 150 square meters would be fully flooded. The only one possible solution was to create a dam of long embankment. Such a project was offered by professor Bazin, the director of Saint-Petersburg Railway University in 1835. The main idea was to traverse the Gulf of Finland with a 20 kilometers long dams from Oranienbaum in the south over Kronstadt to Lisiy Nos on the north bank. Today the Flood Prevention Facility Complex is almost complete, it consists of 25.4-kilometer complex of 11 dams, including a six-lane highway on the top. The dam separates the territory of around 600 square meters from the Gulf of Finland. Now it serves as a part of ring road around the city. Learn how this hydro system was built and how it works from our film.