11 September 2001 in the USA have been the worst terrorist attack in human history: the 19 suicide bombers captured and hijacked four aircraft. The first two rammed the twin towers of the world trade center in new York, the third crashed into the Pentagon, where is the Department of defense. Fourth, before reaching the destination, crashed in Pennsylvania. Killing 2977 people and another 24 were missing. The world plunged into horror and fear.