The changing setting of “William Wilson” is actually a great structuring device. Each segment of the story takes place in a different, specific location. We start at Dr. Bransby’s school, where William meets his double, then move on to Eton for some vice, then finally Oxford for even more vice and even more doppelganger action. (Doppelganger means ghostly double.) The transition to Italy marks our movement into the final segment of the story, in which William offs his double/conscience/self.
Perhaps a more interesting question is: where is the narrator located when he’s telling us this story? You guys work on that and let us know.