On June 4, 1989, Chinese tanks rolled into Beijing'sto crush a student-led protest movement calling for greater political freedom. To this day, the death toll remains in dispute, but it is believed thousands may have been killed.
CBS News' senior foreign correspondent Elizabeth Palmer returned to Tiananmen Square 30 years later, to find its bloody history erased by modern China.
Wu'er Kaixi, who at the time was 21 and was one of the main student leaders of the protests, managed to escape the violence.
"I am the survivor of a massacre," he told Palmer. "I have to live with the guilt."
Although he and the students knew the government was threatened by demands for reform, he said, he thought there was "no way" it would come to "real ammunition and tanks rolling over people."
"You never dreamed it would come to that?" Palmer asked.
"No, no, no, no," he responded.
Tiananmen Square is now a tourist attraction under 24/7 surveillance. Clusters of cameras, for example, are disguised as lamp posts. And the square has been completely scrubbed of anything that might recall the events of 1989.
In fact, the government has so successfully written them out of history, that some young people didn't recognize the most famous Tiananmen picture of a man standing in front of a column of tanks.
"[The] Communist party is extremely nervous about people learning the fact of what happened, which is people stood up and challenged the government," Wu'er Kaixi said.
To make sure it never happened again, the party introduced sweeping economic changes that transformed China into a dynamic power. But at its core, it remains an authoritarian police state.
"We failed miserably," he said. "Let's face it, they are exchanging our economic freedom with our political freedom."
The young idealist paid a personal price: he spent the next three decades in exile.
"I haven't been able to see my parents for the last 30 years," he said, adding "I cannot go back to China and they denied them traveling abroad."
"That's quite a price to pay," Palmer said.
"I'm heartbroken for that," he responded.
He's also heartbroken for the reform movement, once so full of hope, that's now utterly crushed.