The entire east-west width of the core
The entire northern portion of the WTC1 core survived the initial collapse to about the 50th floor with some columns extending as high as the 70th floor. all with no visible trace of buckling. All columns in the 500 and 600 CC rows remained erect and largely interconnected though the initial collapse. One 700-800 column pair was also identified, probably 703-803. There is good reason to believe that some other 700-800 column pairs survived to about the 40th floor because when the west portion of the surviving core did fall, column pair 501-601 was seen to fall with 703-803 in a single collective motion, suggesting all visible columns on the west were interconnected as a considerably larger structure just inside the obscuring dust. These images show that the flooring in the OOS n, nw and ne regions was stripped clean of the surviving columns.
IDENTIFICATION OF TEMPORARILY SURVIVING CORE COLUMNS:
WTC1:
Identification of west side columns
In the case of WTC1, the entire east-west width of the core survived the initial collapse. Animated gif version here
501 is the tallest column of all on the right and 504 is the tall one bending to the right.
We can see how 504 bends to the right and hits 503 clearest in this video:
Columns 504, tall and leaning, and column 501 can serve as easily identifiable landmarks in most all video and photos of the core remnant. We know that columns 501 to 504 mark the boundaries of the the west half of the core. We also know that all columns east of 504 must be from the east side of the core. In the image the east and west sides of the core are distinguishable just by locating columns 501 and 504
This video shows the east side of the core moving and falling independently of the west side:
and images from the video allows us to see the west and east sides of the core and identify the east side columns. This shows the full width of the core. Identification of the full width of the core (8 column pairs total) allows us to conclude that the tallest column on the far west is indeed column 501, confirming the original claim.
Identification of 700-800 core column pair in the core remnant
The distance between 700-800 columns is significantly less than that of the 500-600 separation as a diagram with the spacing dimensions shows:
http://www.sharpprintinginc.com/911_old/Photo_archives/pictures_with_graphics/wtc%20core%20dim.jpg
From the southwest two column pairs forming rectangles with different height to width (h to w) ratios are visible in this image.
The location of the photographer is known to be about 22 degrees from the building's east-west axis. This means:
width we see = actual width x cos(22) (roughly), while cos(22) =.93
Distance between 500-600 = 15.25 ft
between 600-700 = 20.5 ft
between 700-800 = 10.3 ft
distance between 704-805 = 9.5 ft
floor height about 12.5 ft
For the blue rectangle w>h while for the red one h>w giving h to w ratios matching the 500-600 row for the blue rectangle and 700-800 for the red one.