One reason is that the government kept it a "closed" city because of the munitions plants that were here during WWII. Related to that is that Stalin's Bunker was built here secretly. This is the underground facility where the Russian government would have fled to if they had needed to evacuate from Moscow during WWII.
It was never used, and remained unknown and undiscovered until the early 1990s. Now it is supposedly open to the public. But you never know exactly when -- not this week, it turns out. So we just peered around behind the apt complex where it is, and saw the entrance.
I'm off to have a q/a with seminary wives.