The 9-11 Photos - An Attack on Architecture

Twin Towers Aflame on September 11, 2001
Twin Towers Aflame on September 11, 2001. Photo by Carmen Taylor/WireImage/Getty Images (cropped)

The World Trade Center Towers Before the Attack

World Trade Center Twin Towers and the New York City Skyline Before the September 11, 2001 Terrorist Attack
World Trade Center Twin Towers and the New York City Skyline Before the September 11, 2001 Terrorist Attack. Photo by ihsanyildizli/E+/Getty Images (cropped)

On September 11, 2001, a date that has become known as one of the scariest days in U.S. history, terrorists flew commercial jets into three American buildings. What structures were involved that fateful morning? As shown in this September 11 photo timeline, the carnage began in Lower Manhattan, with two prominent skyscrapers.

Built in the 1970s, the World Trade Center (WTC) Twin Towers in New York City were designed to withstand normal fires and hurricane-force winds. According to some reports, engineers believed that even the impact of a Boeing 707 would not bring down the towers.

But no engineer could have prepared for the destruction caused on 9/11 when terrorists hijacked two passenger jets, each much larger than a Boeing 707, and slammed them into the WTC Towers. WTC 1, known as "the north tower" was located geographically north of WTC 2, or "the south tower." The north tower was hit first, from a plane originating in Boston, Massachusetts.

8:46 a.m. - Commercial Jet Hits the WTC North Tower

Top of the New York World Trade Center, smoke, gaping hole where a plan crashed into the skyscraper
A passenger plane hijacked by terrorists struck the North Tower of the New York Trade Center. Photo © Peter Cunningham/Mission Pictures/Getty Images (cropped)

On September 11, 2001 at 8:46 a.m. Eastern Time, five terrorists took control over a Boeing 767 jet, American Airlines Flight 11 from Boston, Massachusetts, and maneuvered the hijacked aircraft into the north tower, WTC 1, of the World Trade Center Complex of buildings.

The plane punctured the tower at floors 94 through 98, but the skyscraper was not yet destroyed. Emergency responders rushed to the scene of what many thought to be a horrible accident.

Smoke Fills the WTC North Tower

Smoke Billowed from the North Tower of the New York World Trade Center
Smoke Billowed from the North Tower of the New York World Trade Center. Photo by Jose Jimenez/Primera Hora/Getty Images (cropped)

Debris from the aircraft sliced through the core of the World Trade Center north tower. The elevator shaft—really a big, empty tube in the middle of the skyscraper—became a conduit or channel for burning jet fuel. As smoke billowed from the upper floors, countless people leaned from the windows, waiting for help. Doors to the roof were locked for safety.

The evacuation of WTC 2, the south tower next door, was not immediately called for. People were just arriving to work and trying to comprehend the bedlam.

9:03 a.m. - Hijacked Plane Hits the WTC South Tower

A Fiery Blast Rocks the South Tower of the New York World Trade Center
A Fiery Blast Rocks the South Tower of the New York World Trade Center. Photo by Spencer Platt/Getty Images (cropped)

At 9:03 a.m. Eastern Time, hijacked United Airlines Flight 175, also originating from Boston's Logan Airport, crashed into the south side of the south tower, WTC 2, within the World Trade Center Complex of buildings in Lower Manhattan.

The plane, a Boeing 767 jet, burst into flames as it struck floors 78 through 84—lower in the building than the aircraft that crashed into WTC 1. Like the first jet into tower 1, the impact on tower 2 destroyed support columns but did not cause the immediate collapse. Both skyscrapers stood tall and burning.

9:43 a.m. - The Pentagon Hit Near Washington, D.C.

Smoke comes out from the west wing of the Pentagon building September 11, 2001 in Arlington, Va., after a plane crashed into the building and set off a huge explosion
The Pentagon Near Washington, DC on September 11, 2001. Photo by Alex Wong/Getty Images

Less dramatic but perhaps more significant was the terror attack on the headquarters of the United States Department of Defense near Washington, D.C. At 9:43 a.m. American Airlines Flight 77 crashed into the building known as the Pentagon, located across the Potomac River from the nation's capital.

While the Twin Towers were commercial skyscrapers—two of the tallest in the world—the Pentagon is a very low building, built like a five-sided bunker. The damage may have been less dramatic to the casual viewer, but the attack on the Pentagon was more meaningful because of the building's military use. The mission of the Department of Defense is "to provide the military forces needed to deter war and to protect the security of our country." Attacking the headquarters of a nation's military was the wartime action that jolted the citizenry from its disbelief. It had been nearly an hour since the first attack in New York City—230 miles northeast of the Pentagon.

10:05 a.m. - The WTC South Tower Collapses

The South Tower of the World Trade Center Collapses September 11, 2001 in New York City
The South Tower of the World Trade Center Collapses September 11, 2001 in New York City. Photo by Thomas Nilsson/ Getty Images (cropped)

The intense heat of the jet fuel cannot melt metal, but heat and flames from the crash probably weakened the steel truss system and steel columns around the facade. Because the second aircraft landed on lower floors, more weight had to be redistributed from the top floors. By 9:45 a.m. Eastern Time, a witness reported that the floors in the south tower were buckling. Videos confirmed the observations.

The south tower was the first to collapse, although it was the second to be attacked. At 10:05 a.m. Eastern Time, in ten seconds, the entire Tower 2 fell upon itself. Tower 1, just north of it, stood smoldering.

10:28 a.m. - The WTC North Tower Collapses

Smoke Rises Over the New York Skyline After the World Trade Center Attack
Forever Changing the Skyline of NYC. Photo by Hiro Oshima/WireImage/Getty Images (cropped)

Because the jets struck the World Trade Center Towers on the upper floors, the weight of the buildings caused their own collapse. As each concrete slab floor gave way, it smashed into the floor below. The massive downward crush of floors crashing, or pancaking, on floors, sent out enormous clouds of debris and smoke.

At 10:28 a.m. Eastern Time, the north tower of the World Trade Center collapsed from the top down, pancaking into dust. Researchers estimate that the rush of air displaced—faster than the speed of sound—caused sonic booms.

The Skeletal Remains of the WTC

An aerial view shows twisted steel and smoke from the site of the World Trade Center terrorist attack September 15, 2001 in New York City
A Smoldering WTC, Four Days After Terrorists Attack. Photo by Gregg Brown/Getty Images (cropped)

After the World Trade Center towers collapsed, white ashes covered the streets and skeletons of shattered walls. Compare the remains seen here with Structure of the New York World Trade Center Twin Towers. Some of the original tridents—the vertical, three-pronged exterior steel cladding—are displayed at the National 9/11 Memorial Museum.

Two Days Later Rescue Workers Search Through the Wreckage

A New York City fireman calls for 10 more rescue workers to make their way into the rubble of the World Trade Center September 14, 2001 days after the September 11, 2001 terrorist attack
Rescue Efforts Began Immediately. U.S. Navy Photo by Jim Watson/Getty Images (cropped)

Two days after the terrorist attack, rescue workers continued to sift through the wreckage of the World Trade Center, searching for survivors.

Five Days Later

Firefighters fighting the smoldering fires with their powerful water jet hoses surrounded by tall buildings and skeletons of facades. New York, 16 September 2001
Smoldering Ruins of Ground Zero. Photo by Viviane Moos/Corbis via Getty Images (cropped)

Flying debris and raging fire from the collapsed World Trade Center towers had an impact on nearby buildings. Seven hours after the Twin Towers fell, the 47-story WTC building 7 collapsed.

After years of investigations, the National Institute of Standards and Technology (NIST) found that the intense heat on the floor beams and girders weakened a critical support column in WTC Building 7.

Ten Days Later, the Survivors' Stairway

The Ruins of Building 6 Is Backdrop to the Survivors' Stairway B from the North Tower
The Ruins of Building 6 Is Backdrop to the Survivors' Stairway B from the North Tower. Photo by Gregg Brown/Getty Images (cropped)

Five days after the terrorist attacks, ruins of the New York World Trade Center buildings still smoldered. Lower Manhattan in New York City seemed like a war zone and became known as Ground Zero.

Ten days later, the meaning of objects and architecture was beginning to be digested. In addition to the iconic trident-designed steel framing, a stairway survived in the collapse of the north tower. More miraculously, 16 people on Stairway B survived as WTC 1 fell around them. The Miracle of Stairway B YouTube Video documents the survivors' journey. The stairway, now called the Survivors' Stairway, is also displayed at the National 9/11 Memorial Museum.

The National September 11 Memorial & Museum also provides learning materials for teachers to use, including an examination of the Survivors' Stairway PDF for grade levels 3-5.

Buildings Destroyed in Lower Manhattan:

In addition to the destruction of the Twin Towers, many other nearby buildings did not survive the collapse of WTC 1 and WTC 2. The next highest skyscraper to collapse was 7 World Trade Center, but there was also 6 World Trade Center, 5 World Trade Center, 4 World Trade Center, and 3 World Trade Center (the Marriott World Trade Center Hotel) that were all destroyed. St. Nicholas Greek Orthodox Church was also destroyed.

The Deutsche Bank Building at 130 Liberty Street (1974) was severely damaged, condemned, and then demolished.

Buildings Damaged, but Eventually Restored:

The Manhattan Community College's Fiterman Hall at 30 West Broadway was also severely damaged, but this  City University of New York (CUNY) building was rebuilt.

The World Financial Center complex, designed by Cesar Pelli in the 1980s, was damaged but became the public's overlook on the building site. The 1907 building at 90 West Street designed by Cass Gilbert was restored, as was the 1927 Verizon Building, One Liberty Plaza, designed by SOM in 1973, the 1935 U.S. Post Office at 90 Church Street, and the Millenium Hilton is back in business.

What has changed? The demolition of the World Trade Center complex altered New York's skyline forever.