According to some, Great Britain held the first world fair of industry and technology(most technology than science; Charles Darwin apparently attended it). As the wiki says, it was in response to a famous French exhibition of science and technology. The wiki article links to a list of exhibitions going back to 1756 and all the way to today and tomorrow!
I've heard of many of these futuristic and current latest technology fairs before looking up the history. George Hale and his first refractor telescope was at a Chicago world's fair in the 1890s. James Burke mentions one in his Connections episode 7,
I had figured the world's fairs had gone away at some point due to the amount of science and technology conferences getting to be so many so often. But, as indicated, they've continued with these to some extent. Turning around, that means the world isn't so concerned about these things as perhaps they once were.
The world's fairs generally led to the building of great architecture cultureal centers for whomever hosted it. The British worlds fair building of 1851 burned down in 1936. For me, I can't help noting maybe not quite a world's fair, but something like it that left Balboa park of San Diego,
Much of the great architecture before the World's fairs were for Kings/Pharohs, religious temples in general.
The latest ability to bring down the costs of dna-nanotechnology using synthetic biology(genetically engineered bacteria) appears to be making noise.