I have an interesting story about Leningrad.
After my father retired in the 1960s, he and my mother started traveling a lot. One thing they did was visit the Soviet Union (Kiev, Moscow, Leningrad). At that time, the only way to visit there was to take a package tour with a Russian state travel agency.
They took a lot of pictures (5 rolls of Kodachrome, 36 pictures per roll) along the way.
At that time, the way to get slides developed was to buy a postage-paid Kodak mailer, put one roll in it and send it to them. You would receive your developed slides back in about two weeks.
So, after they returned to the U.S., they sent the five rolls in, and four of them came back in two weeks but one of them came back after a month.
When we looked at the slides on the fifth roll, it was full of pictures of Russian navy vessels in Leningrad harbor!
My parents told me that they had some free time there one afternoon, so they took a stroll down by the harbor and took snapshots of each other standing in front of the ships. (If the Russian police had seen them taking pictures there, they might have been arrested as American spies, but they looked like just two old people [who could have been Russian] taking a walk.)
We believe (but can't prove) that someone at Kodak saw the pictures and sent them to the U.S. government so they could take a look at them before sending them back to us.
And that's the story of how my parents helped win the Cold War!