(CNN)Here's a look at the Flight 93 National Memorial. It is a memorial to the 40 passengers and crew who died on United Flight 93 on September 11, 2001 near Shanksville, Pennsylvania.
Facts
The memorial site is managed by the National Park Service. The memorial encompasses 2,200 acres and the "Tower of Voices," a 93-foot-tall tower with 40 wind chimes.
Features include the Memorial Plaza, 40 Memorial Groves and the Allée, a formal walking path.
Photos: Photos: 9/11 victims remembered
Photos: Photos: 9/11 victims remembered
9/11 victims remembered – The "Tribute in Light" marks where the World Trade Center buildings stood to commemorate the 11th anniversary of the September 11 terrorist attacks on Tuesday, September 11. The 2001 attacks resulted in the deaths of nearly 3,000 people after hijacked planes crashed into the World Trade Center, the Pentagon in Arlington, Virginia, and a field in Shanksville, Pennsylvania.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – U.S. Defense Secretary Leon Panetta, left, and President Barack Obama stand during a memorial service at the Pentagon in Washington. Obama attended the memorial service, near where American Airlines flight 77 crashed into the Pentagon, to honor the victims of the September 11 attacks.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – A flag is held over the reflection pool during remembrance ceremonies on Tuesday.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – The firefighters of New York City's Engine 33-Ladder 9 observe a moment of silence on Tuesday. The company lost 10 firefighters in the 9/11 attacks.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – Khudeza Begum etches the name of her slain nephew from the memorial of the 9/11 attacks.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – A woman cries as she stands over the reflecting pool at the World Trade Center site on Tuesday.
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9/11 victims remembered – Jillian Suarez, left, consoles Eloy Suarez during observances of the anniversary of the 9/11 attacks on Tuesday.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – A woman cries during the rememberance ceremonies at the World Trade Center site in New York on Tuesday.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – Fire fighters pay their respects at the 9/11 Memorial during ceremonies on Tuesday.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – U.S. military platoons operating out of Lindsey-Forward Operating Base in Afghanistan stand in formation Tuesday during a brief ceremony.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – Scott Willens, who joined the U.S. Army three days after the terrorist attacks of 9/11, pauses at the South Pool of the 9/11 Memorial on Tuesday.
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Photos: Photos: 9/11 victims remembered
9-11 memorial 16 – People pause near the World Trade Center site on Tuesday during a memorial to the victims.
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Photos: Photos: 9/11 victims remembered
9-11 memorial 13 – New Yorkers pause near the World Trade Center site on Tuesday.
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9-11 memorial 14 – An honor guard carries an American flag Tuesday near the South Pool of the 9/11 Memorial.
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Photos: Photos: 9/11 victims remembered
9-11 memorial 15 – David Peters displays his jacket depicting the Twin Towers at the World Trade Center site.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – President Barack Obama and first lady Michelle Obama observe a moment of silence with White House staff on Monday.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – A New York City police officer salutes a flag hanging from One World Trade on Monday.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – A flag sits in a name on the 9/11 Memorial on Monday.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – New York City's "Tribute In Light," a memorial to the victims of the 9/11 attacks, shines from One World Trade into the sky over Manhattan on Monday, September 10, as they are tested for ceremonies marking the 11th anniversary.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – Pictures of loved ones killed in the attacks are displayed at a preview of the National September 11 Memorial Museum's memorial exhibition on Monday in New York.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – Soldiers with the NATO-led International Security Assistance Force pray during a memorial ceremony in Kabul, Afghanistan, on Tuesday, September 11.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – Flowers are left Monday at the Flight 93 National Memorial in Shanksville, Pennsylvania, prior to ceremonies commemorating the 11th anniversary of the 9/11 attacks.
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9/11 victims remembered – U.S. Secretary of Defense Leon Panetta, right, participates in a wreath-laying ceremony in Shanksville.
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9/11 victims remembered – Family members left messages to loved ones killed in attacks.
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Photos: Photos: 9/11 victims remembered
9/11 victims remembered – Defense Secretary Leon Panetta speaks during the wreath-laying ceremonies in Shanksville, Pennsylvania.
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9/11 victims remembered – Germano Riviera carries the Flag of Honor, which displays the names of the victims of the September 11 attacks, across ground zero on Monday.
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Timeline
September 11, 2001 - United Airlines Flight 93, traveling from Newark, New Jersey, to San Francisco, crashes in a field near Shanksville, Pennsylvania. Hijackers were directing the plane towards Washington, DC, but were disrupted by passengers. All passengers, crew and four hijackers are killed.
September 24, 2002 - The Flight 93 National Memorial Act is passed, creating the country's 386th national park.
September 7, 2005 - A design by Paul Murdoch Architects of Los Angeles, "The Crescent of Embrace," is chosen for the memorial. A committee of 15 people, including family members of the victims, chose it out of more than 1,000 entries.
August 31, 2009 - Interior Secretary Ken Salazar announces the National Park Service has reached agreements with seven of eight landowners to purchase the land necessary for the memorial, at an estimated $9.5 million. The eighth parcel, owned by Svonavec, Inc., will be taken by eminent domain after an agreement cannot be reached. This parcel includes most of the crash site.
November 7, 2009 - The groundbreaking ceremony at the memorial site takes place.
September 10, 2011 - The first features of the Flight 93 National Memorial are dedicated and opened to the public. Vice President Joe Biden attends the ceremony.
September 11, 2011 - President Barack Obama participates in commemorations at the memorial site.
May 30, 2012 - The National Park Service completes the planting of the 40 Memorial Groves.
April 2013 - More than 500 volunteers plant 15,500 seedlings across 23 acres. Trees planted for reforestation in the area will serve as a windbreak for the trees in the Memorial Groves.
October 3, 2014 - A fire breaks out at the memorial, destroying the headquarters complex. Although most of the 60,000 tribute items are stored off-site, important items, including the flag that flew over the US Capitol on September 11, 2001, are destroyed. No initial cause of the fire is determined, but arson and foul play are ruled out.
February 6, 2016 - The National Park Service releases a report with the findings of its investigation into the 2014 fire. Improperly discarded smoking material (possibly a cigarette), landscaping mulch too close to the building and flammable decking material may have fueled the fire but investigators were unable to determine exactly how the blaze started. More than 300 photographs and 25 personal mementos were lost in the fire.
September 9, 2018 - The National Park Service hosts the official dedication ceremony of the Tower of Voices.
