Be prepared for a disappointment.
We have seen many pictures displaying the many columns of the cathedral, showing their density and rigorous geometry. We plan to make some good photos, and, at the first attempt, the there comes the problem - the light is so dimmed, that picture demands artificial lighting, but... flash forbidden.
It is not very serious, since the space is so wide that the flash wouldn't reach your subject. The only solution would be a tripod and a long exposure.
OK! We know it, but how come, with hundreds of people, passing in front of your camera?
Forget the good pictures and watch carefully - it will be your best memory.
Oh, the progress... I went there again, with new equipment and time, and now the problem is to choose the best photos. Just wait for my next tips about this marvel.