Harry Potter and the Methods of Rationality
Pages no: 1627
Technically I'm not done yet, because this is still an ongoing story, but so far this is absolutely amazing.
I am following this evolving Harry Potter fanfic with intense interest and appreciation. The beginning is funnier than the later segments, but that follows the arc of the series as well. Well worth a read for a logical yet respectful look at the fallacies of this popular series.