This picture
http://kiewit.oregonstate.edu/images/wtc_sunrise.jpg
allows a fairly clear view through the WTC at sunrise. There's no single core that runs the length of the building.
(It's also very pretty.)
I explain that photo and the other here,
http://concretecore.741.com/
The Concrete Core And Its Hallways
Below on the left is WTC 1 at sunrise. The view is not looking down the hallways, we look nearly along the long axis of the towers core. The vertical line of light in the lower segment is created by sunlight reflecting off the inner core walls then shining out the core hallway.
The North Tower had a core oriented east and west. The camera perspective is not aligned with the hallway as can be seen by the orientation of the south towers roof indicating an oblique view. The light is reflected off the inner south shear wall at a hallway level where there is no doorway interrupting. Notice the very slight interruptions, dark streaks, whole dark floors. The nature of light under these conditions is to blend, blur and obscure solid areas between the light.
We see no light on the left side because the doorways on the north face do not align with the doors on the east. Above that, or the top sky lobby floor, the top floors had a different scheme with some halls on one floor crossing both directions.
The core of the south tower above is oriented north south with its long axis and had 2 halls crossing the short axis. We see no light through it because the doors on our face only reveal a shadowed inner concrete wall corner. See the 2 vertical, central lines in the image below.
Tower on right, the north tower. The interior box columns followed the slight taper of the concrete core to a point then had to continue vertically plumb to the roof as the interior wall of the outside tube of the steel framework. The purpose of this section and photo is to show the space between the interior box columns and the tapering core face at the upper floors. The north tower had hallways crossing perpendicularly every other floor. This picture of the towers is looking due south through the towers.
The north tower core was oriented east west, so we are looking at the wide side. On the right tower fr then project that dddistance down to a cross section. We see, from right to left; a light space from the out side to a dark column which represents the floor space to the interior box column, then there is another narrow light space left of that. That is the space between the interior box column and the concrete core face. Going leftward we see the facing concrete shear wall, then the hallway crossing the narrow axis, then the core face again, then the space between the east core face, then interior box column, then floor space to the east side of the building.
