9/11 Basics: Destruction, Reconstruction, and Memorials

An Overview of Events on September 11, 2001

A wreath was placed by the monument for September 11, 2001 in monument park in Yankee Stadium before the MLB game between the New York Yankees and the Detroit Tigers on September 11, 2003 in the Bronx, New York
Monument Park at Yankee Stadium. Ezra Shaw/Getty Images (cropped)

Before 8 a.m. on a beautiful September morning in 2001, 19 terrorists had gone through security and boarded four commercial aircraft in three different airports. New York's twin towers were destroyed by terrorists on two of these planes. At New York's Yankee Stadium in the Bronx the September 11 Memorial in Monument Park may seem unusual and out of place amongst the plaques to Lou Gehrig, Babe Ruth, Mickey Mantle, and Joe DiMaggio. But this 9/11 plaque, like so many around the United States, is dedicated to the victims and rescue workers of September 11, 2001. The events of 9/11 shocked the world and are remembered and memorialized everywhere. The destroyed skyscrapers changed a nation.

This page is your starting place for finding facts and photos of what happened that day, for buildings associated with these attacks, and for how the people of a nation responded. The September 11 monuments and memorials built over the years — the symbolic architectural designs — help us remember the lives lost when four commercial jets were used to create terror and destruction.

New York Before 9/11

city skyline with two enormous box-like skyscrapers dominating
Twin Towers at the World Trade Center Before September 11, 2001. Getty Images

On September 11, 2001 terrorists crashed two hijacked aircraft into two skyscrapers, the twin towers, at the World Trade Center complex in Lower Manhattan — about three miles southwest of the Empire State Building. Both aircraft,  American  Airlines Flight 11 and United Airlines Flight 175, originated out of Boston's Logan Airport.

The original twin towers were designed by architect Minoru Yamasaki in the 1960s and officially opened as office space in 1973. New York's World Trade Center site consisted of these two skyscrapers and a complex of other buildings.

Pictures from 9/11 suggest the intensity of the smoke and flames — the extreme heat from fires eventually made both skyscrapers collapse. The tall buildings did not topple over on their sides, nor did they fall immediately after the impact of the swiftly moving jets. Instead they collapsed upon themselves that morning. Once the chain reaction event happened, floor falling upon floor, the towers became rubble in a matter of seconds.

To learn why the towers fell, many experts studied the ruins and conducted scientific simulations. Many of the smaller World Trade Center buildings surrounding the twin towers were ultimately destroyed, not because they were directly attacked, but because they were too near the carnage of 9/11. Miraculously, some of the nearby high rise stone buidings built in the 1920s were damaged but not destroyed like the modern 1970s buildings. 

Rescue and recovery began immediately, but few people survived the catastophic collapse. The exception was 16 people on a stairway, which is now on display at the National 9/11 Memorial Museum.

The site was cleared of debris in less than a year. Milestones in planning and building were achieved every year, year after year, until the first new building opened in May 2006.

The Pentagon in Arlington, Virginia

aerial photo of large, low, 5-sided building with trees in the center, a river and monument in the background
The Pentagon Building Before September 11, 2001. Ken Hammond U.S. Air Force/Getty Images (cropped)

On September 11, 2001, five terrorists hijacked American Airlines Flight 77 and crashed it into the west side of the Pentagon building. A timeline of events shows that this was the third building to be attacked that morning. The crash killed all 64 people on the plane and 125 people inside the building. The impact of the crash caused partial collapse of the west side of the Pentagon.

The Pentagon in Arlington, Virginia is headquarters of the United States Department of Defense and one of the largest low-rise office building in the world. The building is called the Pentagon because it has five sides. Set in a five-acre hexagon-shaped plaza, the Pentagon houses thousands of military and civilian employees and also thousands of nondefense workers.

California architects George Bergstrom (1876–1955) and David J. Witmer designed the Pentagon, which was officially opened on January 15, 1943. Oddly enough, ground breaking for the building occurred on September 11, 1941, the year Pearl Harbor was attacked and 60 years before the terrorists struck on 9/11.

The floor plan of the Pentagon echoes its shape, with five floors above ground plus two basement levels. Each floor has five rings of corridors. As a whole, the Pentagon has about 17.5 miles (28.2 km) of corridors.

The building is highly secure. Public tours are given with advanced notice. Because of the military security of the building's architecture and bomb-resistant construction materials, demolition and rebuilding of the damaged area after 9/11 was accomplished in slightly less than a year after the attack. A highly symbolic memorial, one of the many September 11 memorials around the country, was built on the grounds of the crash site.

Shanksville, Pennsylvania

yellow field near a forest, smoking hole being examined by people in protective gear
Field in Shanksville, Pennsylvania, September 2011. Gary Tramontina/Sygma via Getty Images (cropped)

United Airlines Flight 93 was well over Ohio when  terrorists hijacked it and changed its direction — diverting the plane south toward Washington, D.C. The U.S. Capitol or White House were the likely targets for another September 11 attack.

United 93 from Newark was running late that morning. When it was hijacked at 9:28 a.m. ET, the twin towers had already been hit. After passengers realized what was happening on board, many of them made phone calls to their families, who informed them that their hijacking was not unique that day. By 9:57 a.m. the traveler citizens had decided to fight back against the terrorist plot — they stormed the cockpit and tried to retake control of the flight. For three minutes the terrorist pilot maneuvered the aircraft to destabalize the rebel citizens, but at 10:02 the hijackers headed the aircraft nose-first into the ground. A minute later, at 10:03 going 580 mph, Flight 93 crashed in a Pennsylvania field 20 minutes away from Washington, D.C.

Passengers and crew resisted the hijackers. The plane crashed in serene countryside near Shanksville, Pennsylvania. A devastating attack on the nation's capital was prevented by outraged, patriotic citizens on a routine flight.

Soon after the disaster, a temporary memorial was erected near the crash site. Families and friends came to honor the heroes of flight 93. Paul Murdoch Architects of Los Angeles, California and Nelson Byrd Woltz Landscape Architects of Charlottesville, Virginia designed a permanent memorial that maintains the serenity of the landscape. The Flight 93 National Memorial is run by the National Park Service.

Rebuilding in New York

aerial view of lower manhattan, skyscrapers, parks, and the hudson river
Rebuilt Ground Zero, 2016. Drew Angerer/Getty Images

Where the twin towers stood, where thousands of people died, is a memorial surrounded by skyscrapers and a most astonishing "transportation hub," or subway station.

September 11 was not the first time terrorists tried to destroy the twin towers. On February 26, 1993 a truck bomb was used to bring down the north tower, to no avail. The Port Authority of New York and New Jersey (PANYNJ) who owns and operates the World Trade Center site, old and new, might have anticipated that terrorists would eventually finish the job they began in 1993.

Architects and planners faced many challenges as they rebuilt the World Trade Center. While the area was being cleared, plans were solicited. Many architects submitted ideas for new buildings, and out of the hundreds of ideas, plans from seven teams were finalists. Only one master plan was chosen — architect Daniel Libeskind was selected to design a master plan.

Rebuilding after such massive destruction in New York City was one of the most complex projects on the face of the earth. So many people had been affected by the horror of that day — that week, that month, that autumn — that the list of stakeholders grew and grew. In addition to PANYNJ, relatives of the victims, tenants, developers, and politicians were all involved. The Lower Manhattan Development Corporation (LMDC) was established to help in the planning and coordination of the rebuilding.

Because of the infrasctructure beneath Seven World Trade Center, that building went up first, opening in 2006. One World Trade Center, the tallest building in the United States, opened in November 2014 with a design unlike originally proposed. Two World Trade Center, the last of the skyscrapers to be built, has had at least two designs by two entirely different architects.

The amazing buildings on the World Trade Center site have not only changed the skyline of New York City but have also changed the way architects and public policy officials think about modern safety and design. Rebuilding at ground zero has changed the world of construction and architecture for years to come.

Monuments and Memorials

piece of bend iron beam from original twin towers rests on white stone with a bronze plaque on the side
9/11 Memorial in Natick, Massachusetts. Richard Berkowitz/Getty Images (cropped)

Honoring those who died on September 11, 2001 is a painful challenge. Nearly every town across America has a monument or memorial to those who died in the September 11 terrorist attacks. Large and small, each expresses a unique creative vision.

Years of planning went into the spectacular memorial known as Reflecting Absence, reflecting pools that mark the footprint of the twin towers. The visitor steps inside the glass atrium and immediately is confronted with large metal pieces salvaged from the collapse of the twin towers. Walking down ramps and steps, the visitor eventually encounters the iconic slurry wall and the bedrock of what is now history. The National 9/11 Memorial Museum is but one of the many memorials and tributes to remembering 9/11.

Both terrorist planes that struck the twin towers took off from Boston's Logan Airport. The Boston Logan International Airport 9/11 Memorialhonors those who died on that day. Dedicated in September 2008, the airport memorial was designed by Moskow Linn Architects and constructed on a 2.5-acre lot. The memorial is open to the public, 24 hours a day.

Communities across the globe have created small monuments and memorials honoring the souls who lost their lives on 9/11/01. A modest 9/11 memorial in Natick, Massachusetts is a long way from the vast National 9/11 Memorial in Lower Manhattan, yet it shares the same message. A piece of rubble from 9/11 is on display above this gold plaque, which reads:

I stand tall
I do not waiver
I answer the call
To be someone's savior
Fire does not scare me
Nor harm make me weak
I will be there for you
All you need to do is speak
Even if I fail, my brothers
And sisters heed the call
To redouble my efforts
And rescue any and all


  • National Commission on Terrorist Attacks Upon the United States. The 9/11 Commission Report. July 22, 2004
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Your Citation
Craven, Jackie. "9/11 Basics: Destruction, Reconstruction, and Memorials." ThoughtCo, Oct. 29, 2020, thoughtco.com/september-11-destruction-reconstruction-and-monuments-4065281. Craven, Jackie. (2020, October 29). 9/11 Basics: Destruction, Reconstruction, and Memorials. Retrieved from https://www.thoughtco.com/september-11-destruction-reconstruction-and-monuments-4065281 Craven, Jackie. "9/11 Basics: Destruction, Reconstruction, and Memorials." ThoughtCo. https://www.thoughtco.com/september-11-destruction-reconstruction-and-monuments-4065281 (accessed January 28, 2021).