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7. Moscow Metro – Russia
The Soviets were known for their secrecy, but it’s not known whether or not Joseph Stalin commissioned a secret metro line, nicknamed the Metro-2. Allegedly the line was started sometime before the Second World War, and other lines were added up until Stalin’s death in 1953. The lines were meant to transport heads of state as well as weapons, but as of today the Metro-2 is still an urban legend.