Addendum: The Australia Pavilion at Expo 70 is currently under threat but there is a campaign to preserve it called Save the Osaka Expo 70 Australia Pavilion. Visit their Facebook page for more information and updates.
Osaka Expo was the first expo hosted in Asia and it was an incredible example of engineering and architectural finesse thanks to unforgettable temporary pavilions… It was 40 years ago but they look more futuristic than the… Shanghai pavilions [at Expo 2010]. I think they evoke… structural progress and… high-tech concepts... so stunning! Unfortunately most of the buildings were removed... (Osaka Expo '70: Futuristic Pavilions, THEJUICESQUEEZER, June 28, 2010).
This description, posted at an international site dedicated to architecture, design and other related matters, sums up the experience of Expo 70, the world fair held in Osaka, Japan, from mid-March till mid-September 1970. The exhibition, whose theme was Progress and Harmony for Mankind, was Japan’s showcase to the world and proof of its superior technological skills. The 76 nations (plus a British Crown Colony − Hong Kong), as well as three American states and one German city, that took part in it were eager to match the host country, if not technologically then at least architecturally, with the exhibits they displayed inside. The expo was, therefore, an amazing conglomeration of structures, many of them daring in their designs and concepts.