In Russia, there are closed cities that are so secret they’re shut off from the world.

Soviet leader Josef Stalin built them during the Cold War, to give Russian military technology an edge. Some are devoted to building rockets or satellites for the space program. In others, researchers conduct top-secret chemical, biological or nuclear research.

They are known collectively by the acronym ZATO, which stands for “closed administrative-territorial formations.”

Today, there are still dozens of these closed cities scattered across Russia. No foreigners are allowed to visit. Not even Russians can enter, unless they have a security clearance or special papers.

So my ears perked up when I heard about one closed city that had recently opened.

Russian President Vladimir Putin ordered Roslyakovo — a town that has been closed for generations — to open its doors to the world on Jan. 1, 2015.

Roslyakovo lies north of the Arctic Circle. It’s tiny, with about 8,000 people. Most of them are Russian navy, or civilian contractors for the navy, and the local industry is shipbuilding.

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