So I've just read up on The Buzzer for the first time. For those of you who don't know, it's a Russian radio station that's been sending out signals since the Cold War, and no one knows what it's for. Then I started reading about numbers stations and now I wonder how many other strange happenings are out there that I haven't read about yet.

What are some good quirks, oddities and mysteries of the 20th/21st centuries, /r9k/? Not shit like "hurr durr how did Building 7 collapse", but things like interesting spy transmissions on public radio, old Soviet ghost towns, etc. (I've got war on the brain at the moment, but feel free to be creative.)

I know this is more of an /x/ thread, but /r9k/ always has such better stories.