I'm sure Expo 70 was a marvellous thing. I've never been to a World Fair – to me they seem like a thing of the Victorian era, full of fantastical inventions, sights and sounds. But of course they are as much a part of the present and the future…and the past…everywhen, really.
Expo 70 was held in Osaka, Japan and was where the USA displayed a lump of moon rock they'd picked up the year before. It's Landmark Tower inspired the designers of the Valley Forge from Silent Running and the site was used to film the final battle between Gamera and Jiger in the Japanese monster movie…Gamera vs. Jiger, obviously.
And then, there were these stamps.