I don’t know if you’re interested in single subject books, but "The Math Book: From Pythagoras to the 57th Dimension, 250 Milestones in the History of Mathematics" by Clifford A. Pickover is a wonderful book with beautiful pictures. You can look inside at Amazon. If it the reading level is too advanced yet, "G Is for Googol: A Math Alphabet Book" by David M. Schwartz is a good precursor; you can also look inside this book at Amazon.