Getty photographer Spencer Platt's picture of a crowd in Lower Manhattan watching the twin towers burn captures, in one instant, the profound disbelief that held sway in the city and around the world -- a disbelief that inevitably turned to mingled rage, grief, and fear as the scale and the nature of the attack on the country gradually became clear. Here, in a sense, is a portrait of the terrorists' true target: young and old, men and women, civilians of countless races and, no doubt, countless creeds who were, mysteriously, spared, only to bear witness. <br><br>(Photo: Spencer Platt/Getty Images)<br><br>For the full photo collection, go to <a href="http://www.life.com/gallery/59971/911-the-25-most-powerful-photos#index/0" rel="nofollow noopener" target="_blank" data-ylk="slk:LIFE.com" class="link rapid-noclick-resp">LIFE.com</a>