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25 Most Powerful Photos

Jennifer S. Altman, a freelance photographer, took this picture of the towers ablaze, and far, far below them, one woman wearing an expression of pure horror. Five years later, Altman was invited to the home of the woman in red, Rose Parascandola, who had been working at an online-trading company on the 51st floor of WTC 1 on September 11. "She said that I really captured how she felt. She had seen it in the paper, and that it meant a lot to her." For Altman, it was a meaningful photo, as well. "It was a turning point in my career. All my skills came together at once in a professional way. But it also made me very aware of my life; I don't take things for granted."

(Photo: Jennifer S. Altman/WireImage)

For the full photo collection, go to LIFE.com

9/11: The 25 Most Powerful Photos

One decade after 9/11, an unsettling number of images from Ground Zero and its environs remain seared in our collective memory -- unsurprising, perhaps, given the scope and scale of the destruction. But the fact that the deadliest, most visually arresting attacks occurred in New York City also meant that many of the world's best photographers were, in effect, already on the scene when the terrorists struck. Here, to mark the tenth anniversary of 9/11, and in hopes of lending coherence to our shared, turbulent recollections, LIFE.com presents the 25 most stirring, visceral photographs from that day, featuring pictures from the likes of James Nachtwey, Joe Raedle, Spencer Platt, Mario Tama, and other celebrated photojournalists (and one intrepid amateur). These are the pictures we remember: wrenching, indelible photographs that tell the tale of a still-resonant late summer day that changed everything.