Choosing a favorite is really tough. There are so many beautiful churches. But I've got to make a choice, so these were taken inside a chapel that I shouldn't even need to identify because the artist and the images are so well known. The guards were telling people not to take photos, but everyone was doing it anyway (no flash, of course). This was taken in 2005, with a much older digital camera that had far less resolution than today's cameras, and we had to hold our camera very steady. First we are looking up at the ceiling, and then looking straight ahead.
And if you still don't recognize it, well, that's the Sistine Chapel and you have to visit it if you haven't. The Vatican Museum is one of the most fabulous museums in the world.
One thing about that ceiling picture that amuses me. I had a credit card once that allowed card holders to customize the image on the card at no charge. So I sent in that image of the Sistine Chapel ceiling so that I could have a special and beautiful credit card. But the photo was rejected. Why? The credit card company considered it pornographic.