In my senior year of high school, I read Machiavelli's The Prince. I loved it.
He was so incredibly intelligent. I mean, look at this quote from him, "Men judge generally more by the eye than by the hand, for everyone can see and few can feel. Every one sees what you appear to be, few really know what you are."
As for college, I didn't enjoy anything that was required reading. Though I did like it when professors allowed us to choose our own reading topics/novels. My degree is in education, so one of my courses was all about investigating children's literature and forming lesson plans from it. I found tons of great reads that I never knew about as a kid. One in particular was, The Invention of Hugo Cabret. The illustrations were so detailed and imaginative.