Justin Lane-Pool/Getty ImagesNEW YORK, NY - SEPTEMBER 11: A New York City police officer salutes at the North Pool of the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania. (Photo by Justin Lane-Pool/Getty Images)
Mike Segar-Pool/Getty ImagesNEW YORK, NY - MAY 15: Former New York City Mayor Rudy Giuliani speaks during the opening ceremony for the National September 11 Memorial Museum at ground zero May 15, 2014 in New York City. The museum spans seven stories, mostly underground, and contains artifacts from the attack on the World Trade Center Towers on September 11, 2001 that include the 80 ft high tridents, the so-called "Ground Zero Cross," the destroyed remains of Company 21's New York Fire Department Engine as well as smaller items such as letter that fell from a hijacked plane and posters of missing loved ones projected onto the wall of the museum. The museum will open to the public on May 21. (Photo by Mike Segar-Pool/Getty Images)
Spencer Platt/Getty ImagesNEW YORK, NY - MAY 21: The National 9/11 Flag is viewed at the 9/11 Museum where it is being displayed for the first time on May 21, 2015 in New York City. The National 9/11 Flag, an American flag recovered nearly destroyed from Ground Zero, was restored in "stitching ceremonies" held across the country. (Photo by Spencer Platt/Getty Images)
Spencer Platt/Getty ImagesNEW YORK, NEW YORK - SEPTEMBER 11: Friends and family of victims of the September 11 terrorist attacks, pause at the National September 11 Memorial during a morning commemoration ceremony for the victims of the terrorist attacks Eighteen years after the day on September 11, 2019 in New York City. Throughout the country services are being held to remember the 2,977 people who were killed in New York, the Pentagon and in a field in rural Pennsylvania. (Photo by Spencer Platt/Getty Images)
Drew Angerer/Getty ImagesNEW YORK, NY - SEPTEMBER 8: An aerial view of the National September 11 Memorial & Museum and the Oculus Transportation Hub, September 8, 2016 in New York City. New York City is preparing to mark the 15th anniversary of the September 11 terrorist attacks. (Photo by Drew Angerer/Getty Images)
John Munson-Pool/Getty ImagesNEW YORK, NY - MAY 15: A quote from Virgil fills a wall of the museum prior to the dedication ceremony at the National September 11 Memorial Museum May 15, 2014 in New York City. The museum spans seven stories, mostly underground, and contains artifacts from the attack on the World Trade Center Towers on September 11, 2001 that include the 80 ft high tridents, the so-called "Ground Zero Cross," the destroyed remains of Company 21's New York Fire Department Engine as well as smaller items such as letter that fell from a hijacked plane and posters of missing loved ones projected onto the wall of the museum. The museum will open to the public on May 21. (Photo by John Munson-Pool/Getty Images)
Spencer Platt/Getty ImagesNEW YORK, NEW YORK - SEPTEMBER 11: Friends and family of victims of the September 11 terrorist attacks, pause at the National September 11 Memorial during a morning commemoration ceremony for the victims of the terrorist attacks Eighteen years after the day on September 11, 2019 in New York City. Throughout the country services are being held to remember the 2,977 people who were killed in New York, the Pentagon and in a field in rural Pennsylvania. (Photo by Spencer Platt/Getty Images)
Allan Tannenbaum-Pool/Getty ImagesNEW YORK, NY - MAY 15: People on the memorial plaza watch a video feed of the opening ceremony for the National September 11 Memorial Museum at ground zero May 15, 2014 in New York City. The museum spans seven stories, mostly underground, and contains artifacts from the attack on the World Trade Center Towers on September 11, 2001 that include the 80 ft high tridents, the so-called "Ground Zero Cross," the destroyed remains of Company 21's New York Fire Department Engine as well as smaller items such as letter that fell from the hijacked plane and posters of missing loved ones projected onto the wall of the museum. The museum will open to the public on May 21. (Photo by Allan Tannenbaum-Pool/Getty Images)
Spencer Platt/Getty ImagesNEW YORK, NEW YORK - SEPTEMBER 11: John Timson, 10, pauses at the National September 11 Memorial where his uncle Andrew Fisher's name is etched into a panel with other victims during a morning commemoration ceremony for the victims of the terrorist attacks Eighteen years after the day on September 11, 2019 in New York City. Throughout the country services are being held to remember the 2,977 people who were killed in New York, the Pentagon and in a field in rural Pennsylvania. (Photo by Spencer Platt/Getty Images)
Justin Lane-Pool/Getty ImagesNEW YORK, NY - SEPTEMBER 11: Robert Peraza, who lost his son Robert David Peraza, pauses at his son's name at the North Pool of the 9/11 Memorial during tenth anniversary ceremonies at the site of the World Trade Center on September 11, 2011, in New York City. New York City and the nation are preparing to commemorate the 10th anniversary of the 9/11 terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. Security has been heightened in both New York City and Washington D.C. following a possible car bomb threat. (Photo by Justin Lane-Pool/Getty Images)
