This historic event took place on October 30, 1974 in Kinshasa, Zaire. The Rumble in the Jungle was a fight between George Foreman (at the time, the heavyweight champion) and Muhammad Ali. They each received a fee of $5,000,000.
Ali wasn't expected to win, but he knocked out Foreman in the 8th round, becoming heavyweight champion for the second time in his career.
A documentary about the fight, When We Were Kings, was release in 1996 and won an Oscar. The trailer for the film is below. The movie Ali reconstructs the fight.