A very young Cassius Clay, long before he changed his name to Muhammad Ali, training at Fifth Street Gym. (from Muhammad Ali: the Birth of a Legend)

Ali training shadow boxing underwater in a swimming pool (from Muhammad Ali: the Birth of a Legend)

November 15, 1962: A young Ali stands over boxing legend Archie Moore in the fourth round of a 12-round fight. Ali won by a knockout.

May 25, 1965: Ali stands over fallen champion Sonny Liston during their title bout in Maine.

March 8, 1971: Joe Frazier (left) hits Muhammad Ali during the 15th round of their heavyweight title fight at New York's Madison Square Garden. Frazier died of cancer in 2011.

January 28, 1974: Ali (left) in a 12-round non-title fight with Joe Frazier at Madison Square Garden, New York.

October 30, 1974: Defending heavyweight champion George Foreman takes a savage right from Ali during the famous Rumble in the Jungle fight in Zaire.

October 30, 1974: Referee Zack Clayton steps in after Ali knocks down George Foreman in the eighth round of the Rumble in the Jungle.

October 1, 1975: Ali lands a right on Joe Frazier during the ninth round of their title fight in Manila, Philippines.

1979: With Aussie TV personality Bert Newton at the Logies.

July 19, 1996: Lighting the Olympic flame at the Atlanta Olympic Games.

December 12, 1999: British soccer player David Beckham with Ali at the BBC Sports Personality of the Year Awards in London. Ali won the award for Sports Personality of the Century.

November 9, 2005: US President George W Bush presents Ali with the Presidential Medal of Freedom.

September 24, 2008: At the Clinton Global Initiative, a gathering of politicians, celebrities, philanthropists and business leaders, in New York.

November 13, 2010: Muhammad Ali onstage during a fundraiser in New York for the Michael J. Fox Foundation.

March 23, 2013: With singer Jennifer Lopez at Muhammad Ali’s Celebrity Fight Night in Phoenix, Arizona.

July 28, 2012: At the Opening Ceremony at the 2012 Olympics in London.

September 27, 2014: Ali at an awards ceremony in Louisville, Kentucky.