This. I had the same feeling on seeing The Triumph of Death by Pieter Bruegel the Elder in the Prado. [0] It's one thing to see the painting in a book. It's another thing to turn the corner into a room and see the full 20 square foot landscape in front of you. (It's still one of my favorite paintings of all time.)

[0] https://en.wikipedia.org/wiki/The_Triumph_of_Death