The attack on the World Trade Centre was the most watched event in human history. And the footage seen of that day came not only from TV cameras, but also from workers, tourists, and passers-by, each of whose lives would change dramatically when confronted with the sight of the attacks. David Friend has uncovered the stories behind those images - from the street-level shots of the north tower crumbling to fire-fighters raising the American flag over the rubble. In "Watching The World Change", he traces the images back to their sources and charts their impact over the next seven days. That week was the beginning of a digital age, a moment when all the advances in television, photography, and the Web converged on a single event. A brilliant chronicle of how we process disaster.