Today is the 100th anniversary of the famous (and first-ever) World Championship title change, with Frank Gotch beating Georg Hackenschmidt on April 3, 1908, in Chicago, IL.
Some background from Wikipedia:
George Hackenscmidt won a world championship tournament [in Vienna, Austria, November 1901] to win the title. Hackenschmidt won several other tournaments in Paris, France; Hamburg, Germany; Saint Petersburg, Russia; Elberfield, Germany; and Berlin Germany in the same year. He also won the European Greco-Roman championship title from Tom Cannon on September 4, 1902 in Liverpool, England. He won the recognition of being the World Heavyweight Champinon on January 30, 1904 in London, England by defeating Ahmed Madrali. Hackenschmidt defeated American Heavyweight Champion, Tom Jenkins, on May 4, 1905 in New York City, New York to become the recognized World Champion in North America.
Frank Gotch held the title for four years, and was the second longest World Heavyweight Champion in history behind Bruno Sammartino who later became the longest WWWF Championship and World Champion, holding the title for seven years and three months.