The Soviet fear of U.S nuclear attack against the Soviet people was well founded. Now we know that there was a discussion about nuking the Soviet Union by the U.S and the UK in Operation Unthinkable. At any case, I do not think that this underground bunker or hidden city built during the early days of the Cold War is good enough now to defend the Black Sea Fleet from sudden nuclear attack. But the fact the U.S once considered nuking majority cities in the USSR tells one that it would try again if it thinks that it can get away with it. This is really the moral point of the existence of this underground bomb shelter. Russia must defend its homeland with everything technologically possible from imperialistic aggression. If that means upgrading this bunker then it must be done. Of course, tourists and the local people might not like it- so perhaps a new underground city might be better alternative to returning this now museum space to a military space.

I think places like this could be a tourist gold mine to the state that keeps them open. The hidden harbor is obsolete now and it would be horribly expensive to either demolish it or try to convert it to another use. But foreign tourists would pay to tour the old place. There are a lot of us who were raised on Cold War novels and who would love to see artifacts - as long as we knew they were just old history, of course. :)