The Seattle Space Needle was built for the 1962 Worlds Fair. Every year for my kids birthdays we trundle up the top to celebrate them. It's an awesome restaurant with some stunning views. Sadly, the towers in Seattle itself are now higher than the observation tower, so they're not quite as good as they used to be, but it's still worth a visit.
But the meals themselves are fantastic. We put the kids birthday cards on the ledge on the side, and as the restaurant revolves, people take the card and add birthday greetings. Kind of a neat tradition, and it usually takes about an hour for the card to roll back to us.