Between science fiction and fantasy, The Castle of the Carpathians by Jules Verne is characterized by true ambiguity generic. The author says the novel, but the demented throughout the novel. He wants to anchor the events in a real setting and uses the geography of Romania and Transylvania to create a universe ‘repository’. It is a real generic instability. But at the same time, the whole geography opens up a place, the castle, converges to this attraction, and it succeeds. However, this place could be in any other place on earth. So it’s a real literary curiosity than devoting so much effort to build a world-oriented referential to take him to a place that is outside of space and time. It is this ambiguous relationship between geography and imaginary, between fiction and fantasy that this essay will attempt to elucidate.