Oh, oh! The Dark Tower, by Stephen King. For decades I thought it would go unfinished, and since the entire tale actually spans almost all of his 30+ novels, not just the Dark Tower books themselves, it is quite the undertaking, but even if you just read the seven books in the Tower series itself, which is fine...it does EXACTLY what you asked...builds, and builds and then has a grand climax that actually takes you...where? Back to the beginning? A new beginning? The End? VERY ambiguous. Many of its readers could argue forever about exactly what it all meant. And yet I was enormously satisfied. Thats strange, isnt it? I felt like it was the only ending possible to do the story justice, one in which the totality of possibilities and impossibilities was encompassed. Masterful. At least from my perspective. I am sure others felt cheated.