Let's imagine that, in anticipation of Western warheads, all the German doors at the stations are closed. Hundreds of thousands of people hid from the nuclear bombardment in the stations and tunnels below. All these people consume a huge amount of air for breathing. And where to get it in kilometers of tunnels, this air, if the hermetic doors are closed?
For such a case, a special long-range ventilation facility was built on the northern end of the First stage of the Leningrad metro. The object is serious, without any irony. It is designed to create overpressure and ventilation of the subway in the event of a nuclear or chemical attack, when the hermetic doors leading to the surface will be closed, in order to avoid the ingress of dangerous substances into the atmosphere of the subway.
Only a few elements of this object can be seen on the surface. The building of the special facilities service of the metro, the exhaust pipe of a diesel power plant (next to the building Lesnoy Prospekt, 17 building 3), a vent with an elevator inside (in the courtyard of the building at Lesnoy Prospekt, 25) and some other small things.
Below, of course, there is an air intake command post, the diesel power plant itself, several gates with a subway. One of them goes to the 3rd track of the station Ploshchad Lenina and is designated according to the documents as a special purpose path. It is blocked by a lattice gate, the traffic lights after the gate are turned in the opposite direction.
You can also pay attention that one of the exits from the facility is located right next to the railway depot of the Finlandsky railway station, and from the other end of the facility in 1978, a special communications tower was erected over the city - the mobile VHF radiotelephone communication system "Altai".
There is an opinion that some of the pedestrian tunnels of the object go to the stage to the station Vyborgskaya. There are several abandoned tunnels on this site, which appeared due to the repeated transfer of the route during construction. Officially, there are storerooms located there.