Proceedings surrounding the September 11 attacks

thumb|300x300px|The basement of the J. Edgar Hoover Building, the FBI's headquarters, was used as the base of operations for PENTTBOM PENTTBOM (sometimes spelled as PENTTBOMB) was the FBI's investigation into the terrorist attacks against the United States on September 11, 2001 (9/11), in which 19 members of al-Qaeda hijacked four U.S. commercial airliners in an attempt to crash them into national landmarks. The name is short for "Pentagon/Twin Towers Bombs", the "bombs" being three planes that had hit the Pentagon in Virginia, and the Twin Towers (1 and 2 World Trade Center) in New York City.