First, those doors are 30 inches. None of the doors are the size of the tiles. That hallway is 16 feet wide (a little less due to dry wall on the walls on each side). Those really are 4x4 squares aligned as a diamond.
To answer your question about where the actual main entrance ...
SP is clearly in front of that column. That column is located 44 feet from the start of the west hall looking north. (52 feet from the southwest vestibule inner doors.) That column is 1 foot wide. So the main entryway starts 45 feet down. About 10 to 15 feet behind SP. That main entry area is 24 feet wide. After that the hall extends another 45 feet until you get to the north hall way and 53 feet to the vestibule doors on that end.
I know the position of that column by calculating the numbers using the actual measurements of the building and combined with the tax information for that building and I know the width of the main entry and the length and width of the entryway on the north end of that hall (coincidentally it is the same on the south side, except it is combined with the patio area and the car port area in the tax info). Thus, I also know the width of that hallway.
You can see the pile of numbers I posted in reply to Scout for more about the building, and the various dimensions of things.