To Kill a Mockingbird definitely. I just reread the book this year and watched the movie.
The Man in the Iron Mask by Alexandre Dumas, which is the end book of the D'Artagnan Romances. These start with The Three Musketeeres and ends with The Man in the Iron Mask. I read this last book before I ever read
The Three Musketeers. I admit that it may have been better to have read them in order to get the whole life story of the musketeers before reading the last book, but I do love the whole story of
The Man in the Iron Mask. [These are in our MR Patricia Clark Memorial Library (in four volumes) -
Dumas, Alexandre: D'Artagnan Romances, Vol 1]
I think 'classic' is just something that is from another era (I think it could count from our parents time and on into the past). A time we are not living in that still has universality - family, emotions, relationships, etc..