Narnia

All closets were allegedly portal to the magical world of Narnia. This included the Closet in the Sitting Room of the Strange and Wonderful House, but it was designed to test users' faith in this fact because the real doorway was actually the back of the closet, with what appeared to be its back wall acting as the door. Hence, only if they thought to open it despite their initial disappointment, would the would-be travellers realise the Closet really was a portal to Narnia after all. (PROSE: Our Strange and Wonderful House: The Closet in the Sitting Room)