When we are asked to believe that a boeing 757 penetrated through yards of reinforced concrete walls at the Pentagon we have to strain out imaginations to do so. Look at it this way...the 757 strikes the first wall, and only the fuselage goes through...crosses about 50-60 feet of space and goes through another wall,...then another open space and carries on through another wall..another similar open space , and another wall, another open space, then another wall and another open space, and yet another wall,aoither open space, and finally punches a large clean hole in a final wall. ...Three rings in all, with another building section crossing the fuselage's path.(see link).