It is understood that there's a massive underground facility housing a strategic command post.
According to one recent account ["We Keep Building Nukes For All the Wrong Reasons", By Bruce G. Blair, The Washington Post Sunday, May 25, 2003; Page B01] "Kosvinsky is regarded by U.S. targeteers as the crown jewel of the Russian wartime nuclear command system, because it can communicate through the granite mountain to far-flung Russian strategic forces using very-low-frequency (VLF) radio signals that can burn through a nuclear war environment. The facility is the critical link to Russia's "dead hand" communications network, designed to ensure semi-automatic retaliation to a decapitating strike. (https://www.globalsecurity.org/wmd/world/russia/kosvinsky.htm)