Canadian sprinter Ben Johnson (center) was stripped of his 100 meter gold medal at the 1988 Seoul Olympics when he tested positive for stanozolol. He admitted having used steroids when he ran his 1987 world record, so that was rescinded too. His main rival, US athlete Carl Lewis (right), tested positive in1988, but successfully blamed the traces of banned stimulants on cold medication.

US track and field world champion and Olympic gold medalist Marion Jones forfeited all prizes dating back to 2000, admitting in 2007 that she’d been doping that far back. She confessed to lying about it to a grand jury investigating performance-enhancer creations by the Bay Area Laboratory Co-operative (BALCO), which supplied more than 20 top athletes, and was sentenced to six months in jail.

The German sprint star and world champion in 1991 for the 100 and 200 meter distance tested positive for clenbuterol in 1995. A comeback attempt failed.

Dieter Baumann, German 5000-meter Olympics champion of 1992, later tested positive for Nandrolone and was banned for two years in 1999, causing him to miss the 2000 Sydney Olympics. He argued that someone had contaminated his toothpaste. He came back in 2002, at the age of 37, to win silver over 10,000 meters at the European Championships in Munich.

Ekaterini Thanou and her training partner Konstantinos Kenteris failed to attend a drugs test on the eve of the Athens 2004 Summer Olympics. Later that day they were hospitalized, claiming they’d had a motorcycle accident. They withdrew from the Games, and investigators ruled the accident had been staged and they were criminally charged with making false statements to authorities.

The most high-profile case in professional cycling: The US Anti-Doping Agency in 2012 found Lance Armstrong guilty of using performance enhancing drugs, stripped the seven-time Tour de France winner of his titles and banned him for life. In January 2013, Armstrong told US television personality, Oprah Winfrey, how he lied without detection for years between 1998 and 2004.

Argentine football legend Diego Maradona tested positive for Ephedrine at the soccer World Cup in the US in 1994 and was excluded from the tournament. Three years earlier he had been found to have taken cocaine.

Claudia Pechstein is the most successful Olympic speed skater, ever. In 2009, she was accused of blood doping and banned from all competitions for two years. She claimed an inherited condition was the reason for irregular levels of reticulocytes but failed to win a long legal battle. She returned to competition in 2011, winning bronze in the 5000 meter event at that year’s World Championships.

Russia’s Svetlana Krivelyova won shot put gold at the 1992 Olympics and the World Championship in 2003. At the 2004 World Indoor Championships she was awarded gold after the winner was stripped of her title for failing a drugs test. In Athens, 2004, she won bronze only after the winner was disqualified for doping. A re-test then found drugs in Krivelyova’s, and the medal was rescinded.

South African long-distance runner Gert Thys entered World Championships and Olympic Games. He won the 2006 Seoul International Marathon but was disqualified after testing positive for the steroid Norandrosterone. Thys contested the ban, pointing to laboratory errors: the same technician had analyzed both his samples, a breach of testing rules. In 2012 he was exonerated.

Jamaican former 100-meter world record holder Asafa Powell, his teammate, three-time Olympic medalist Sherone Simpson, US American sprinters Tyson Gay and Veronica Campbell-Brown all failed doping tests this summer. Powell was one of the world’s most-tested athletes in the run-up to the London 2012 Summer Olympics. He is exploring legal options.

The Olympic Games were held in Ancient Greece from c. 776 BC-393 AD, until they were banned by Emperor Theodosius as a "pagan cult." French academic Pierre de Coubertin initiated their revival in Athens from April 6-15, 1896. Those Games were opened by Greece's King George. The Olympic Hymn, composed by Spyridon Samaras with lyrics by Greek poet Kostis Palamas, was performed for the first time.

Less than two years after the end of World War I, the Olympics were held in Antwerp. The Olympic flag, designed in 1913, was flown for the first time. The six colors on the flag - the white background plus blue, yellow, black, green and red rings - contain the colors of all other national flags. The athletes' Olympic oath (pictured) was also introduced as a commitment to fair and clean sport.

By the 1928 Summer Games in Amsterdam, much of the present-day protocol had been established. It was the first time the Greek national team entered the stadium first during the parade of athletes. Participating countries follow in alphabetical order according to a language chosen by the host country (usually its main language). Athletes from the host country march in last.

For the first time in 1936, a torch was relayed from Olympia, where the Olympic flame was lit, to Berlin - a tradition that has since become inseparable with the Games. The idea, said leading sports historian Manfred Lämmer, stemmed from Jewish archaeologist Alfred Schiff. Some 3,000 athletes participated in the relay and track star Fritz Schilgen (pictured) carried the torch into the stadium.

As Nazi flags were raised in Berlin for the Games, a much less foreboding flag incident occurred. When the teams from Liechtenstein and Haiti met at the opening, they were shocked to discover that their flags were identical. Liechtenstein responded by adding an emblem to theirs.

Yoshinori Sakai - also known as the Hiroshima Baby - was born on August 6, 1945, the same day the United States dropped an atomic bomb on Hiroshima. He was just 19 when he carried the Olympic torch into the stadium in Tokyo, setting a symbol for world peace and creating an unforgettable Olympic moment. The 1964 Games were the first to be held in Asia.

The Olympic Games are inseparable from the political climate. Dick Palmer, secretary of Britain's Olympic team (front right), is carrying the Olympic banner to represent the absent British Olympic Association in protest during the opening ceremony in Moscow. Japan and West Germany were among those that joined the US-led boycott and didn't attend to protest the 1979 Soviet invasion of Afghanistan.

In a spectacular display of sportsmanship, Catalonian Paralympic archer Antonio Rebollo didn't run the Olympic torch up to light the flame, but shot it with his bow and arrow at the opening of the 1992 Games in Barcelona. Apparently, he was instructed to shoot just above the cauldron, while an Olympic official lit the actual flame in a perfectly choreographed maneuver.

If the flame lighting in Barcelona was impressive, four years later in Atlanta, it was tear-jerking. Boxer Muhammad Ali was a controversial figure in the US after going to court for refusing to serve in the Vietnam War, but was also a hero for his athletic performance and commitment to his Muslim beliefs. While lighting the flame in 1996, he was visibly shaking due to Parkinson's disease.

In recent years, the artistic element of the otherwise strict protocol of the opening ceremony has taken on greater significance, though the motto of peace remains consistent. In 2004 in Athens - the birthplace of the Games - eccentric Icelandic singer Bjork performed her song "Oceana" and donned a dress that slowly unfurled over the athletes' heads to reveal a 10,000-square-foot world map.

Beijing pulled out all the stops in 2008 for an opening ceremony said to cost $100 million. (London in 2012 cost just $40 million.) Exactly 2,008 percussionists rigged with glowing sticks performed on fou drums, ancient Chinese percussion instruments. The thundering performance and show of unity was a highlight of the three-hour-long opening ceremony, which incorporated over 14,000 performers.

In London in 2012, Queen Elizabeth became the first head of state to have officially opened two Olympic Games. And she did so in style - with a stunt double "parachuting" into the opening ceremony. She opened her first Games as Queen of Canada in Montreal in 1976. In her speech, she declared per protocol: "I declare open the Olympic Games of 2012, celebrating the XXX Olympiad of the modern era."