Hall of Famer Mickey Mantle was among the most prolific home run hitters in baseball history, and baseball lore tells us that he hit the longest home run in baseball history.
It was April 17, 1953 when The Mick crushed a Chuck Stobbs pitch, knocking the ball out of Washington's Griffith Stadium. Lore tells us that the homer traveled 565 feet, which would make it the longest home run in baseball history, by most accounts.
The actual distance was likely more around 510 feet. More, from baseball-almanac.com:
" ... the entire baseball world was lead to believe the ball had traveled 565 feet from home plate to the point where it landed. In truth, that figure derived from the distance from home plate to the place where a neighborhood child retrieved the ball. Since this home run was the only one that ever cleared those bleachers during decades of major league and Negro League competition, it is genuinely deserving of recognition. However, the actual distance in the air was probably about 510 feet."
Regardless, Mantle's legendary blast will remain a signficant part of baseball lore moving forward.