(quote) Denise-906256 said: Bernie, Is the Chartes Cathedral the one with the thick walls having small outside opening graduating to very large inside?
Having never visited, I can only talk about photos and plans I have seen. Just me, most of the cathedrals of the era have small openings in traffic sense, but many seemed to consciously strive for larger window/light openings. At that time there were many increases in the size of unencumbered interior spaces, and Chartres may be one of the largest in its time.
The progress in construction materials, methods, and design is interesting.
If your question is specifically whether the openings in the walls themselves were all like a cone with the larger diameter inside, I don't know.
Many good books on Gothic cathedrals are still in print. If you can find Allan Temko's book on Notre Dame de Paris, it may be helpful.