If you look at the picture in the post above, you'll see an outline down at the bottom clearly marking the impact point of some object. Resembles the view of an airplain from the back doesn't it? However, the highest impact point was only 26 feet, not 44 which is what a 757 would need. It was also 90 feet wide at the base. The 747 would've needed 124 ft. of damage. Furthermore, there were some support beams still actually in place where the 747 should have gone through.
and the damage to the outer ring is of little importance.
Where is the energy going to go from the impact? Along the same path as the momentum. The plane went through 3 buildings, coming to rest in the 3rd ring.