To observe the decay of uranium, it was necessary to go deep underground, where cosmic rays do not penetrate. Therefore, in 1940, Soviet physicists used the service rooms of the then-new "Dynamo" station for their experiments.
But this is not the only case. For example, in the 1970s, several metro tunnels were turned into plantations to study the possibilities of growing mushrooms in extreme conditions. According to another version, the mushrooms were needed for medicine production. In the 1990s, the experiments were stopped, the equipment was removed, and the tunnels were sealed.
