On September 11, 2001, the world as we knew it changed, forever. Most of us have emotional and shocking recollections of the moment when we first saw the images of a smoking World Trade Center. We soon learned that our country was the victim of a terrorist attack, including two planes hitting the World Trade Center towers in New York City, another crashing into the Pentagon, and a fourth going down in a field in Pennsylvania on its way towards the White House.

Known now just as “9/11,” the 11th day of September is a time to mourn, remember, and honor the fallen from that day, as well as celebrate our resiliency and American ideals. Here are 20 facts about 9/11:

  1. The terrorist attack on September 11, 2001 that targeted the World Trade Center and Pentagon ended up being the largest loss of lives from a foreign attack on American soil, even significantly more than the Pearl Harbor attack. It was also the greatest loss of lives in world history for any single terrorist attack.
  2. In all, the attacks claimed 2,996 lives and wounded 6,000 more. To date, only 1,632 victims have been identified, leaving as many as 1,121 unidentified. Of all the fatalities, 343 were New York City firefighters, 23 were New York City police officers, and 37 were Port Authority officers.
  3. Thanks to the heroic efforts of these rescuers, a total of 18 people were found alive amidst the rubble of the World Trade Center and saved.
  4. Before 9/11, an average of 50,000 people worked in the World Trade Center towers every week day, with another 40,000 coming and going in the buildings.
  5. It took an unimaginable 3.1 million man hours to clear all of the rubble and debris from the fallen World Trade Center towers, with 1.8 million tons of wreckage hauled away.
  6. It wasn’t until mid-December – 100 days later – that New York City fire fighters could extinguish all of the smoldering fires caused by the 9/11 attack.
  7. Part of the cleanup effort including sifting through for remains and personal possessions to be returned to their rightful families. In all, cleanup crews found 65,000 items, including 437 watches and 144 wedding rings.
  8. Most people don’t realize that another World Trade Center structure collapsed that day, not just the Twin Towers. In fact, Building 7 of the WTC complex fell later that afternoon, although it was not publicized.
  9. Around the world, the top Google queries the week after the 9/11 attacks were: 1) Osama bin Laden; 2) The World Trade Center; 3) CNN; and 4) Nostradamus.
  10. Of course, the 9/11 terrorist attack in New York City wasn’t the first time terrorists targeted the World Trade Center. In 1993, a car bomb exploded in the complex parking subfloor, killing six people.
  11. Sadly, there are numerous documented cases of warnings before 9/11. San Francisco Mayor Willie Brown (at the time) said that he received a warning late Monday evening from airport security telling him not to fly the next day.
  12. A Princeton University computer-generated algorithm program called the Random Event Generator predicted a “cataclysmic event was about to unfold” only three hours before the attack.
  13. While it’s the loss of life is the real tragedy, the economic losses caused by the attacks are unprecedented. It took $750 million just to clean up the World Trade Center complex, and the estimated total price tag from 9/11 is now estimated at $123 billion.
  14. That bill includes the $60 billion cost of damage to the WTC complex and surrounding buildings, infrastructure and subway facilities, $40 billion to fund the emergency anti-terrorism package approved by Congress in 2001, $15 billion aid to the airlines, and $9.3 in insurance claim payouts.
  15. The attacks affected all New Yorkers in some way. Attendance at churches and synagogues was up 20%, and alcohol sales were up 25% as well. In fact, nine months after 9/11, the birthrate at New York City hospitals was 20% higher than the same month in 2000.
  16. Almost immediately after 9/11, the Victims Compensation Fund was established to help victims and their families. The fund operated from December 2001 to 2003 and received 7,408 applications for personal injury and death claims, disbursing funds in 5,560 of those cases.
  17. On January 2, 2011 – a decade after the attack – President Obama signed the James Zadroga 9/11 Health and Compensation Act of 2010, expanding the help the original Victims Compensation Fund could offer to victims.
  18. There have been numerous tributes and memorials designed to honor the victims of the 9/11 attacks, including a National September 11 Memorial & Museum by the site. But none is more iconic than the twin beams of light projected straight into the air on the site of the World Trade Center. Called The Tribute in Light, the memorial was made of 88 searchlights pointed towards the heavens, and is still reproduced every year even now that the Towers have been rebuilt.
  19. The venerable financial investment firm Cantor Fitzgerald operated out of WTC and lost 658 employees that day. To honor their fallen coworkers and other 9/11 victims, they’ve been donating the proceeds from their work to world wide charities every September 11.
  20. There’s increasing groundswell support for a national holiday to honor 9/11 in the U.S. September 11 is now designated as a Day of Remembrance, not a national holiday like Pearl Harbor Day on December 7.