Required reading books that actually stuck with you?

Inspired by the recent post someone made about how 1984 really stayed with them. I would also say that that book really stuck with me even almost a decade after reading it for class in high school.

So what required books you’ve read during your school years actually stuck with you? For me it’s 1984 and Memoirs of a Geisha. I remember both books very distinctly despite only reading them once over a decade ago.