How old is Poland's Wieliczka salt mine?
Learn about the Wieliczka salt mine in Poland, which operated for hundreds of years and features intricately carved sculptures and architectural elements made of salt.
Encyclopædia Britannica, Inc.
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Contunico © ZDF Studios GmbH, Mainz; Thumbnail Gary Todd; © Georgios Kollidas/Dreamstime.comOverview of the invention of the telephone, with a focus on the work by Alexander Graham Bell.
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© 2026 Thomson ReutersOne robot ran a sub-9 second 100-meter dash in a 2026 competition—and promptly crashed into a padded wall.
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Encyclopædia Britannica, Inc.Muslim women working in a factory.
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Encyclopædia Britannica, Inc.Still with the hope of not directly engaging in the war, the United States provided defense materials and other support systems for the Allied forces at the dawn of the 1940s.
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Contunico © ZDF Studios GmbH, Mainz; Thumbnail Lieut. Michael M. Dean/Canada. Dept. of National Defence Library and Archives Canada/PA-140126In the aftermath of World War II, many Europeans lacked adequate food, shelter, and resources.
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Encyclopædia Britannica, Inc.Soviet foreign minister Vyacheslav Molotov, having negotiated the German-Soviet Nonaggression Pact of August 1939, being greeted by German foreign minister Joachim von Ribbentrop and other officials in Berlin. From “The Second World War: Prelude to Conflict” (1963), a documentary by Encyclopædia Britannica Educational Corporation.
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Encyclopædia Britannica, Inc.The German invasion of France, May 1940; from The Second World War: Triumph of the Axis (1963), a documentary by Encyclopædia Britannica Educational Corporation.
