Here you can see the second story roof covering the space between "E" & "D" and "D" & "C" rings. That is why those rings did not have typical exterior walls. The space in the A/E Drive goes to the ground (5 stories) but the first floor has no windows. The two "blow-outs" in the left of this photo are a roll-up door and a regular door. There was only one penetration through the brick and that is what is called the "exit hole". To the north (or right) of the renovation line where the exit hole is there were no door openings in the A/E Drive.

This is an example of what the space between the collapse and the "exit hole" looked like. It would have had wood frame walls built in to divide the space up. This is actually from one of the upper floors because the columns are smaller. One floor 1 the columns were 21 inches square. Each progressive floor the columns were smaller.