The great underground construction, known as Stalin's Bunker, was built in 1942, during the WWII
Soviet government with Joseph Stalin was planned to move into this bunker in the case of Moscow defeat
A lot of trucks were used in order to move a big amount of soil during the building of the bunker. At that time nobody knew what was in that trucks
It was a time of war, and it was a building of local authorities. Authorities always had their secrets
People had no intentions to reveal these secrets, because it was dangerous
According to some rumors, bunker was built by prisoners. It is not true. There were builders form Moscow Metropolitan
And they have kept this secret well. According to KGB and FSB, information about the bunker was not revealed until 1990 
It was declassified by the authorities. Before 1990 no one here had any idea about this "Object number 1". Though there were some legends
The bunker is about 40 meters (131 ft) deep. It could provide shelter for over 600 people 
In 1990s the bunker was turned into a museum, and everyone is welcomed to visit it
