Photograph by National Geographic, 2011

ON ANY GIVEN DAY IN 2001, nearly 25,000 people departed on flights in the United States. On the early morning of September 11, 19 men associated with the Islamist extremist group al Qaeda under the direction of Osama bin Laden boarded four flights intending to hijack the planes and use them as weapons to destroy major American landmarks.

American Airlines Flight 11 carried 76 passengers, nine flight attendants, two pilots, and five of the hijackers. About 15 minutes after takeoff, the plane was overtaken by the terrorists, who stabbed two flight attendants and a passenger.

Two other flight attendants made calls from the coach cabin to report the hijacking to American Airlines officials on the ground. One, Betty Ann Ong, stayed on the phone for approximately 25 minutes, calmly reporting from the plane to an American Airlines reservation office in North Carolina. The other, Madeline Amy Sweeney, reached the flight services office in Boston and provided information to help identify the hijackers. As the flight crew worked to keep passengers calm, the plane turned south, descending rapidly. After 45 minutes in the air, Flight 11 approached Manhattan, flying south along the Hudson River. At 8:46, the plane crashed into 1 World Trade Center, the north tower, instantly killing everyone on board and hundreds in the building.

First responders mobilized immediately. News helicopters in the area began reporting the crash, generally presuming an accident had been caused by a small aircraft. Nearby onlookers recalled staring up in disbelief and horror, and seeing the sky fill with white paper blowing out from the tower’s gash.

UNITED AIRLINES FLIGHT 175 departed Logan International Airport en route to Los Angeles with 11 crew members and 54 passengers, including five hijackers. At roughly the same time that Flight 11 struck the north tower, Flight 175 was hijacked. Two passengers and a flight attendant made phone calls to people on the ground, reporting the hijacking. Passenger Brian David Sweeney reached his mother, Louise, and told her that the passengers were considering rushing the cockpit to regain control of the plane. Shortly after 9:00, the plane crashed into the south tower, killing everyone on board and hundreds inside the building.

Visualization by Squared Design Lab

At its core, the 9/11 Memorial’s purpose is to honor the people who are no longer with us because a group of Islamist terrorists took them from us far too soon. The memorial also offers a tremendous opportunity to bring people together in much the same way that we saw the world come together immediately following the attacks. For those who may never have a chance to visit in person, we hope this book offers a way of honoring the victims. The act of remembering is a measure of tribute in and of itself.

The 9/11 Memorial Museum will be another way to ensure that these men, women, and children are remembered for generations to come. Opening one year after the memorial, the museum will include an exhibition in tribute to the 2,982 lives lost—full of photographs, recordings, and loving notes. Emanating from that core, the museum will be a dynamic, 21st-century institution, the authoritative source for an evolving understanding of 9/11 with a focus on the future.

The staff of the 9/11 Memorial feel a deep responsibility, having come to know, in some way, those killed, through thousands of stories told so vividly and graciously by their loved ones. May the water, light, bronze, soil, and stone of the memorial help to heal the scar in our city’s and nation’s heart.

A Place of Remembrance is available for purchase at the National Geographic Store.

National Geographic is a proud sponsor of the National September 11 Memorial.

Watch this video honoring the 9/11 Memorial, featuring the voice of Jon Stewart: