There are various conspiracy theories that attribute the preparation and execution of the September 11 attacks against the United States to parties other than, or in addition to, al-Qaeda. These include the theory that high-level government officials had advance knowledge of the attacks. Government investigations and independent reviews have rejected these theories. Proponents of these theories assert that there are inconsistencies in the commonly accepted version, or that there exists evidence that was ignored, concealed, or overlooked.
The nature of the collapse of the two World Trade Center towers and the nearby 7 World Trade Center (in this photo, the brown building to the left of the towers) is a major focus of 9/11 conspiracy theories.
Criticism of the reports published by NIST on the destruction of the World Trade Center buildings plays a central role in theories about an alleged controlled demolition. The picture shows the simulated exterior buckling of 7 WTC during the collapse.
Excavating equipment was cooled by water spray due to concerns about melting from underground fires.
The Pentagon, after collapse of the damaged section
A conspiracy theory is an explanation for an event or situation that asserts the existence of a conspiracy by powerful and sinister groups, often political in motivation, when other explanations are more probable. The term generally has a negative connotation, implying that the appeal of a conspiracy theory is based in prejudice, emotional conviction, or insufficient evidence. A conspiracy theory is distinct from a conspiracy; it refers to a hypothesized conspiracy with specific characteristics, including but not limited to opposition to the mainstream consensus among those who are qualified to evaluate its accuracy, such as scientists or historians.
The Eye of Providence, as seen on the US $1 bill, has been perceived by some to be evidence of a conspiracy linking the Founding Fathers of the United States to the Illuminati.
The Warren Report
Third Reich Nazi anti-Semitic propaganda poster entitled Das jüdische Komplott ("The Jewish Conspiracy")