I visited Chartres, and the stained glass windows were breathtaking. I bought a bunch of books with photos of the Cathedral...I have no idea where those books are, but I’m inspired to find them now.
The internet is an amazing resource; I think of it as the present day equivalent of the Great Library of Alexandria. Check out the link posted above to the Chartres windows. It serves as a key; click each link to open up a large image of the particular window.
Like you, I also visited the Sistine Chapel but it was prior to the restoration. The colors were subdued as a result of centuries of soot. You can take a 360 degree, virtual tour at this VATICAN web site.
Michelangelo was truly a Renaissance giant.