Tiananmen Square

In April 1989, tens of thousands of Chinese students began calling for democratic reform and a halt to rising corruption. The protests centered around Tiananmen Square, where people camped out and more than 1 million marched for change. After two months of rallies demanding reform, the government ordered the army to clear the square and on June 4 troops opened fired on hundreds of unarmed students and civilians in the area.

June 5 however, saw one last act of defiance: a solitary man who placed himself in the way of a row of tanks, as if -- with nothing but his skinny body and two shopping bags -- he might take on the entire military. The tanks tried to reroute around him, but he stepped back into their line and continued to block them. He climbed onto the first tank and knocked against its hull -- in an act at once staggeringly defiant and yet oddly pleading. Then he disappeared into the crowd, never to be identified. Twenty years later, the impact of his actions remains as uncertain as his name.

Even 20 years later, it remains like that man we all remember, known everywhere and yet unknowable.