The Soviets had dozens of these types of underground facilities scattered around, that were just abandoned intact when the Soviet Union fell. They were rally points for the military if they ever went to war. They were largely forgotten about, such was Soviet secrecy.
The Slavyansk facility in Ukraine that the Russian rebels took over during the Civil War is just one example. A mile and more of tunnels filled to the ceilings with tens of thousands of Infantry small arms dating back as far as WW2, including shoulder launched AA missiles, and tens of millions or rounds of ammunition. From what I have read it was supposed to be a rally point for three to four “ Tier C” light infantry divisions, had the balloon ever gone up with Wesren Europe.
I cannot find it now, but another tunnel complex was found a decade ago in a sparsely populated eastern area., Milesof tunnels filled with a hundreds 50’s and 60’s era Soviet tanks and support equipment, to be activated by reserve divisions if the Chinese ever invaded.
The Soviets had dozens of paper Army Divisions, with small command staffs of officers, that were to use these caches if it were ever needed.
That all went away when the Russians reorganized, but the storehouses were simply locked, abandoned and forgotten in the chaos that followed.
Wow!