Case file · Secret facility (alleged)
Metro-2, Moscow's secret underground railway
Since the early 1990s Russian writers have claimed that a secret second metro, 'Metro-2' (code-named D-6), links the Kremlin, ministries, airports and bunkers deep under Moscow; the government has never confirmed it.
1992 CE · 55.69, 37.51 · status: claim
The account
The writer Vladimir Gonik popularised the idea after interviewing officials; a 1991 US Defense Department report spoke of secret lines. Urban explorers ('diggers') say they have seen sections. Metro-2 became a staple of Russian fiction and video games, including the 'Metro 2033' series.
The sceptical view
Some deep bunkers and service tunnels certainly exist; the full system described is not documented.