What's Your Favourite Classic Book?

By Thismomloves @ThisMomLoves
So, I just read The Great Gatsby for the first time (yes, because of the movie!) and I realized that I really haven't read many English classics.

I was a French major, so most of my English lit was studied in high school, where I remember poetry, a lot of modern selections, and Shakespeare (specifically Romeo and Juliet and Hamlet. In OAC English, my partner and I were assigned a presentation on the "Appearance vs Reality" theme in Hamlet, and we used Counting Crows' "Mr. Jones". Reflect on the lyrics, it was quite brilliant of us, I think. Another duo was presenting on the relationship of the brothers, and used a clip from The Lion King, when Scar kills Mufasa. Also quite deep for 18 year olds, in my opinion.)
So clearly I remember English class, but not many classics. With summer coming and hopefully some beautiful, sitting-by-the-pool days ahead, I'd like to catch up on some great books that I may have missed, so I'm looking for suggestions. What's your favorite classic? Is there one that you go back to on a regular basis, or that made such an impact on you the first time that you'll never forget it? Please leave a comment and let me know (don't feel like you have to write me an English essay and prove your thesis or anything, just a title is fine if that's all you want to provide!) and I can add it to my summer list. Thanks!