Like details about how normal people lived their lives, not just the higher class. You can learn more about the things they wore, or how they cooked, or made clothes - stuff like that! And sometimes there are letters or diaries that people found; it's really cool!

And with art, it's about learning more about the materials and techniques they used. A lot of them fell out of practice, but trying to preserve those methods, or at least keep good records of them, is a huge thing.