The standoff, just east of the square, was captured by newspaper photographers and TV news crews. The standoff lasted but a few minutes, but was so tense with drama that witnesses recall it feeling like an eternity.

Photographer Jeff Widener, whose photo of the incident is the best known, was working then for the Associated Press. He says he has "always felt 'Tank Man' was like the unknown soldier. He will always symbolise freedom and democracy".

No one knows for sure the man's name, or whether he's dead or alive. Still, American's Time magazine named him one of the century's top 20 revolutionaries, whose "moment of self-transcendence [was seen] by more people than ever laid eyes on Winston Churchill, Albert Einstein and James Joyce combined".

But it's unclear whether "Tank Man" has ever been aware what an enduring symbol he became, because in China, the image remains barred. (The identity of the tank driver, too, remains unknown to the public.)

Shortly after the incident, a British tabloid identified "Tank Man" as Wang Weilin, 19, the son of Beijing factory workers. But efforts to substantiate the report ran into dead ends.