Well I thought, and I thought, and I thought. It seems to me that the books that felt the longest weren’t! How surprising is that. (Note that is a statement, not a question.)
I could have sworn Tess of d’Urbervilles was the longest book IN the world, but nope, Tess was only 149,682 words. Anna Karenina took quite possibly my whole life, (In January – Marchish) and she only came in at 349,168. Watership Down? Like under 200k! Good gracious!
It was clear my perceptions were off. Also, when I first thought about this question I was looking at page counts but I soon realised that was stupid then I started looking at word counts. I found this awesome link on some crazy forum - HERE it is; take a gander. There’s a lot of books listed there with their word counts!
Upon doing this oh so important, (read: procrastination from life), research I quickly realise that I am smack dab in the middle, (actually the first 30%), of one of the top ten longest books in English; A Suitable Boy – 591,554. Yay. And also, I have two behemoths standing in front of me, looking for all the world like Goliath: Gone With The Wind – 418,053; and War and Peace – 587,287.
Now to actually answer the question. All of this research showed me that the longest book I have ever read was a whopping 513,000 - Les Misérables. You want to know something weird? I flew through it. I read that sucker so fast, I read it again right away. Huh.
[and can i just say? i hate the new linky police. stupid people who didn't follow the rules and ruined it for everyone who already was. because of them i have to do this http://crazy-for-books.com/2011/08/book-blogger-hop-819-822.html due to my actual real hidden link not being good enough for one reason or another today. great.]