9/11

On September 11, 2001, terrorists by the name of Khalid al-Mihdhar, Nawaf al-Hazmi,, Mohamed Atta, Marwan al-Shehhi, and Ziad Jarrah were avid extremists associated with Al-Quaeda .Osama Bin Laden, was responsible for the attack on the U.S. These men were responsible for the 4 planes causing mass destruction.
Two of the airplanes crashed into the World Trade Center located in New York City.  One of the planes crashed into the Pentagon( headquarters for the U.S military). The 4th plane was of fought down by passengers which made the terrorists miss their target.
  Since the event people gather with open arms to honor people who unfortunately died during the 9/11 attack.