IT WAS unquestionably the most terrible day of our age. September 11, 2001. The day that Americans will remember.

On that day almost 3000 innocent people died when terrorists hijacked four civilian planes. Two of the planes struck the twin towers of New York’s World Trade Center. One nosedived into the Pentagon in Washington. And one crashed into a field in Pennsylvania thanks to the brave efforts of passengers who stormed the cockpit.

As Americans begin their day of mourning, we’ve compiled 7 images to remind you why this day was so momentous.

While for some, words just couldn’t describe the horror these men have seen.
The force of the world’s highest towers collapsing reduced buildings to ash which coated survivors in a ghoulish cloak.
WTC 2, or the South Tower, was the second of the Twin Towers to be completed, the second to be hit by a plane on September 11th, and the first to be destroyed.
At 9:03 AM, Flight 175 slammed into the southwest face of the tower, creating an impact hole that extended from the 78th to 84th floors. Upon impact, large fireballs emerged from the southwest, southeast, and northeast faces, and east corner.
The impact rocked the tower, causing it to sway several feet. The jet hit the right side of the face at an oblique angle, and much of the fuselage emerged from the east corner. It appears that a large portion of the estimated 10,000 gallons of fuel Flight 175 was carrying at the time of impact exited the southeast and northeast faces of the building in the spectacular fireballs. Seventeen minutes after the North Tower impact, a number of photographers were able to capture the South Tower fireballs on film.
The South Tower began its precipitous collapse at 9:59 AM. At first the portion of the tower above the crash zone began to tilt to the southeast, while the first explosions of dust began at the crash zone. Then, at about 2.5 seconds the top began to fall, and its rotation decelerated. At about the 6.5-second mark, the top was completely swallowed up by the huge growing dust cloud.
The search continued in vain. The United States were shocked.
Engineers say that the World Trade Centers had an unusual design, where much of the structural load was carried by the exterior shell of the building rather than central columns. So when that shell was pierced, the buildings were weakened significantly, precipitating their collapse. Source: AFP