City 40, or what is today known as Ozersk, is a closed city in Russia that the Soviet Union created during the Cold War. City 40 didn't appear on any maps until 1991, allowed no outsiders to enter, and for a long time, no insiders were allowed out. It wasn't until very recently that the Western world has even become aware of Ozersk, and it took a brave documentary crew sneaking cameras through the heavily guarded gates for any footage of the city to escape.
That footage shows Ozersk as the heart of the Russian nuclear program and its residents as the people charged with keeping that heart beating. The denizens of the cloistered city were treated to luxuries that the rest of the country was denied but also exposed to dangers that others were not. While there is (and will always be) much that outsiders will never know about what happens inside those gates, here is what we do know about the surreal, dangerous, closed-off world of City 40.