During the cold war, the Soviets
built a secret underground submarine base in the Crimea region
of Ukraine at the town of Balaklava. The base was so top secret
that the entire town was off limits and the base itself was hidden
from sight. It was built in a mountainside to avoid western spy
planes and was designed to withstand a direct nuclear weapons
blast. The subs that operated out of this facility were equipped
with nuclear tipped torpedoes and other weapons.
After the Soviet Union fell,
the base was de commissioned in 1993.