We assembled a team of reporters and researchers, including professional fact checkers and the editors of PM, and methodically analyzed all 16 conspiracy claims. We interviewed scores of engineers, aviation experts, military officials, eyewitnesses and members of the investigative teams who have held the wreckage of the attacks in their own hands. We pored over photography, maps, blueprints, aviation logs and transcripts. In every single instance, we found that the facts used by the conspiracy theorists to support their fantasies were mistaken, misunderstood, or deliberately falsified.