The fall of the Berlin wall is probably one of the 3-4 "Where-were-you-when..." events that I remember in my lifetime. I remember turning on the TV and seeing people dancing on top of the wall and being struck with a strong sense of cognitive dissonance, wondering if I was watching some war-of-the-worlds style fiction. I don't remember even today if this was a surprising event to the whole world, of if it was just I who was holed up in some ignore-the-outside-world zone, but it certainly was a stunning surprise to me.
It was truly a great day, in my mind more great than 9/11 was bad, so it is kind of amazing to me how much it is already almost forgotten. In the late 1970's, I had the opportunity to take the East Berlin tour through Checkpoint Charlie to see the wrong side of the wall. Many Americans I have talked to had the same reaction to this tour -- that it was meant to be one long propaganda spiel for communist East Germany but in fact was pathetically self-mocking. The propaganda failed because even the writers of the propaganda could not conceive of how wealthy the west was compared to the East. So when they bragged that 70% of the residents had running water or that "almost" all of the city had been rebuilt from the war 30 years later, Westerners were unimpressed.
Update: Remembering the victims of communism.