Astronomical Clock in Prague. Everyone makes it seem like this crazy wild event when the clock hits the hour and throngs of people gather in the square to watch it every hour and are disappointed when it hardly does anything.
VERY cool considering the time period in which it was made, very very interesting, but not an extravagant display by any means.
I found it more fun to go and watch the the people get disappointed every hour after I had seen it the first time.