From ducks on the rowing course to mystery gold medallists, here are 20 unbelievable but true facts about the Olympic Games.
Australia's Harry Pearce stopped rowing during a race in 1928 to let a family of ducks pass in front of his boat. He won that quarter-final and eventually the gold medal.
1972 100m favourites Eddie Hart and Rey Robinson missed their quarter-final because their coach was keeping to an outdated schedule.
Last-minute Ethiopian selection Abebe Bikila won the 1960 Rome marathon barefoot. He defended his title in shoes at Tokyo.
China dominates the medals tables now but didn't win its first Olympic gold medal until 1984. Shooter Xu Haifeng became an instant legend and is still revered in the 'Middle Kingdom'.
Greek gymnast Dimitrios Loundras won bronze at the 1896 Athens Olympics aged just 10 years and 218 days old.
Oscar Swahn, a Swedish shooting expert, is the oldest medal winner after claiming silver at age 72 in 1920.
Tug of war was contested as a team event in the Olympics from 1900 to 1920.
The marathon course in Munich in was arranged in the shape of the Games mascot, Waldi the Dachsund.
Six US cities bid for the 1956 Olympics but all lost out to Melbourne.
The US men's swimming team won 12 out of 13 gold medals at the 1976 Olympics.
In 1976 an official relit the flame using his cigarette lighter after rain put it out.
The Seoul Olympics had an official song called Hand in Hand which topped the charts in 17 countries.
Real birds were used in the shooting competition in 1900. More than 300 birds lost their lives.
Eric 'The Eel' Moussambani Malonga swam his 100m freestyle heat at the Sydney Games in 2000 in 1min 52.72s, outside the time for the 200m world record.
Greece, Australia, France, Great Britain and Switzerland are the only countries to have had representatives at every Summer Olympic Games.
1932 women's 100m gold medallist Stella Walsh was shot dead in an armed robbery in 1980. An autopsy revealed she had male genitalia.
Romania's Nadia Comaneci was awarded the first 10 in a gymnastic event when she won gold in the uneven bars at Montreal in 1976.
A random French boy was chosen as coxswain in the victorious Dutch coxed pair at the 1900 Paris Games. His identity remains unknown.
Equestrian rider Princess Anne was the only female athlete not required to submit to a sex test at Montreal in 1976.
15-year old swimmer Violet Walrond became NZs first female Olympian in 1920, but couldn't leave her accommodation unless to compete or attend team functions.