The multiple attacks made on the US by terrorists using hijacked aircraft on 11 September 2001 have proved attractive to conspiracy theorists. Theories may include reference to missile or hologram technology. By far, the most common theory is that the attacks were in fact controlled demolitions, a theory which has been rejected by the engineering profession and the &lt;a href="9/11%20Commission"&gt;9/11 Commission&lt;/a&gt;.