The Century of Progress World's Fair - held in Chicago in 1933 and again in 1934 - was among the most successful World's Fairs of all time, actually turning a profit. It was also the launch-pad for Tru Vue's toy-format 3D filmstrip system, which documented the Fair over 8 different filmstrips. This is the first one.
First used by man in the Paleolithic era, the interconnected Wookey Hole Caves stretch far into the earth, through vast, flooded chambers created by the underground River Axe. Used as a Doctor Who shooting location in "Revenge of the Cybermen",
The post-war Raumbild-Verlag Siegfried Brandmüller series "Denmark" shows a number of great views of Copenhagen, as well as a couple of terrible ones.