Huckleberry Finn. A Tale of Two Cities.
I haven't read many of either Twain or Dickens books, but have a suspicion that both authors have several timeless books.
I mean they definitely have very clear settings of time and place, but the stories have a timeless qualities.
I think Don Quixote would fit that as well, and maybe a lot of Dumas.
Moby Dick. (I have yet to finish it, I got 1/2 way through it and put it down some time ago I need to get back to it)