9/11 terrorist Waleed M. Alshehri, who was on AA flight #11, which crashed into the North Tower of the World Trade Center lived in this house in Vienna:
502 Orrin Street, Vienna, Virginia
Daniel Pipes notes:
One of the 9/11 suicide hijackers, Waleed M. Alshehri, had lived in a large rental house in Vienna, Virginia. His and his friends' comings and goings (loud parties, pistol shooting, fancy cars with out-of-state license plates, people "always walking around out front with cellphones," a van permanently parked outside the home with a Middle-Eastern man in it monitoring a scanner or radio) aroused suspicions. The neighbor across the street, John E. Albritton, called federal authorities and another neighbor says residents complained to the FBI.
Sadly, the concerns of Mr. Albritton and others could not prevent the 9/11 attacks.