Buenos Aires On the eve of the 1968 Olympics in Mexico City, the mood was explosive with protests against a heavy-handed government. Buoyed by the worldwide student protest movement, tens of thousands of students in Mexico City marched to the open Plaza de las Tres Culturas, hoping to catch the international spotlight before the games.
Instead, on October 2, 1968, ten days before the Olympics were to open, up to 300 demonstrators - nobody knows precisely how many - were killed when military and paramilitary troops opened fire.
Italian journalist Oriana Fallaci described what happened in the Tlatelolco Massacre, named after the surrounding neighbourhood. "I have been shot at, they have stolen my watch, they left me to bleed to death there on the floor of the Chihuahua (building)," she wrote of Mexican security officials.
She compared the attacks to covering Vietnam, where at least there were "barricades, refuge, trenches, holes, whatever, that you can run to for cover. Here there was not the slightest chance to escape," she wrote.
The dead were victims of the Mexican government's attempt to squelch the protests before the start of Latin America's only Olympic Games.
The Olympics themselves were heavy with political protest. US medal winners Tommie Smith and John Carlos raised clenched fists in the famous Black Power salute on the podium, expressing silent anger over the slaying of US civil rights leader Martin Luther King earlier that year.
Czechoslovakian gymnast Vera Caslavska the winner of four gold medals looked away as the Soviet anthem was played for fellow winners, just six weeks after her country had been invaded by Warsaw Pact troops led by the Soviet Union.
Forty years later, with the dichotomy between human rights and the Olympics again making headlines ahead of Beijing 2008, the Tlatelolco Massacre has come to be called Mexico's "Tiananmen Square."
"The demand (for more democracy) and the fact that the start of the Olympics was coming led (the government) to choose the hardline once and for all, to carry out an action that would teach a lesson, so to speak," historian Lorenzo Meyer of the Centre for International Studies of El Colegio de Mexico told Deutsche Presse-Agentur dpa.
In 1968, the Mexican regime was in the 40-year-grip of the Institutional Revolutionary Party (PRI) despite elections. It wanted to make a good impression with the Olympics.
"The whole world would have its eyes on Mexico, but behind the screen of Olympic buildings there would remain extreme poverty, the stratification of a society that was hostile to those usually forgotten, the cruelty of a government willing to pretend anything," said Mexican author and journalist Elena Poniatowska.
She explained that while '68 protests in France were triggered by the demand for "increased opportunities," in Mexico they rose amid "a rejection of authoritarianism."
"In fact, 1968 can be seen as the beginning of the collapse of Mexican authoritarianism," Meyer agreed. It was the "breaking point, when the regime sacrificed its usual approach of co-opting criticism, which had always been its secret weapon."
The Mexican regime held on for so long because it had never resorted to large-scale repression, Meyer said. But they could no longer ignore the student movement of 1968.
"We do not want the Olympics, we want a revolution," many shouted on the streets.
For 40 years, the massacre has been shrouded in secrecy. The government stood by its estimate of "more than 30 and less than 40" dead. It insisted that student snipers had shot at the protestors, and the Mexican media largely went along with it.
But foreign media and witnesses substantiated claims that around 300 were killed, thousands more were injured and over 2,000 were arrested. Suspicion fell on then-interior minister and later president Luis Echeverria.
It wasn't until 1998 that Echeverria conceded that the shooting came not from student snipers but from security officers.
In 2006, following the 2000 demise of the PRI, Echeverria was put under house arrest for nine days, then released due to the statute of limitations.
Like the students, the athletes who demonstrated against the status quo in Mexico 1968 were pushed into oblivion.
Gold medal winner Smith and bronze medal winner Carlos were booed by the crowd and expelled from the Games for what the International Olympic Committee termed "a deliberate and violent breach of the fundamental principles of the Olympic spirit."
Caslavska was ostracized by the new regime in her country.
Just like it took Echeverria 30 years to acknowledge the government had massacred its citizens, it took decades for Smith, Carlos, Caslavska and the Mexican protestors to see the fruit of their protests.
Today, the Czech and Slovak republics stand free from the Soviet yoke. An African-American senator, Barack Obama, stands a good chance of being elected US president. And Mexico has an open multi-party system.
