Low and behold, the Prado Museum. Said to have the greatest collection of (I think) 12th through 19th century art in all of Europe. Go, Prado. Naturally, no photography allowed but look who you’re talking to.
If you’re interesting in visiting the Museo del Prado, allow for a few hours to actually see the entire thing. There’s more art inside those walls than you’d imagine.
I noticed several artists, or perhaps time periods, used window coverings or panels for their paintings. Not only was there a painting inside, but also some sort of sketch or painting on the outside as well. There was also an interesting table in the center of the Bosch room depicting the 7 deadly sins. It’s much harder than you’d think to pick out each one.