OK. How about a very simple example that is only approximately true, just to get you into the ballpark?
Let's ignore the walls of the WTC and just pretend that the WTC was made up of floors only. 4 inches of concrete. Let's say 8 inches of steel beams. 4+8=12.
12X110=1320 inches, or 110 feet.
Piled up perfectly with no gaps or imperfections, just the flooring would have been 110 feet in the sky. That's 9-10 stories tall, which would have been visible above a ten foot fence from two blocks away 3 days after the attacks.
All this is silly to talk about, because floors didn't fall. Dust that had very recently comprised the material that made up a floor was falling, but nothing like an intact floor was ever falling during the final destruction of WTC 1 and 2. "What used to be a floor" was falling, but so was everything else that used to make up the World Trade Center.
The reason you had such a short pile at Ground Zero is because almost the entire building became dust. No, they didn't sell the steel to China. What used to be steel spread out over lower Manhattan in the form of particles.
Not much was left to pile up (compared to the mass of the buildings).