The Walls Came Tumbling Down.

Photo: Even a superpower can be brought low: To say that no one anticipated the tragic events of September 11 would be an understatement. When 19 men hijacked four U.S. airliners, driving three into the World Trade Center and the Pentagon, the planet gasped in horror. For a brief moment, most of humanity was united in a spasm of shock and mourning. It seemed the very anchors of our world had come loose. The United States had awakened to a terror many nations had known, but that Americans, comfortable and secure, had never imagined. That day would change the destiny of a nation--and set in motion a chain of events that seemed to dim all that had come before.

Photo: The worst trauma may have been felt in Lower Manhattan--at Ground Zero--by the firemen who lost comrades by the hundreds and by the office workers who were caught in the debris. But it was an American president, untried and unadmired on the world stage, who faced the greatest challenge of his life.

Photo: There was no place for criminals to hide: The year brought its share of surprises--and controversy. On June 29 the `Butcher of the Balkans,' Slobodan Milosevic, was ...