The 1896 Olympic Games featured the first Olympic marathon,
which followed the 25-mile route run by the Greek soldier who brought news of a
victory over the Persians from Marathon to Athens in 490 B.C. Fittingly,
Greece's Spyridon Louis won the first gold medal in the event. In 1924, the
distance would be standardized to 26 miles and 385 yards.
(http://www.history.com)