The Olympic Charter bans political, religious or racial demonstrations, but politics have rarely been far from the Games.

In Melbourne in 1956, the Soviets and Hungarians clashed in the swimming pool, while in 1968 in Mexico City black US athletes protested about racism.

In Munich in 1972, Palestinian gunmen killed 11 Israeli athletes, while in 1980 and 1984 the United States and Soviet Union boycotted each other's Games.

Here, we look back at what happened:

Includes archive interviews with Hungarian and Soviet water polo players Ervin Zador and Yuri Shlyapin -- US athletes Tommie Smith and John Carlos -- Ankie Spitzer, widow of Israeli fencing coach Andrei Spitzer -- British Olympic runner, Lord Coe -- US lawyer and rower, Anita Defrantz.

Slideshow production Paul Kerley.