As Marco tells the khan about Armilla, which "has nothing that makes it seem a city, except the water pipes that rise vertically where the houses should be and spread out horizontally where the floors should be," the spider-web city of Octavia, and other marvelous burgs, it may be that he is creating them all out of his imagination, or perhaps he is recreating fine details of his native Venice over and over again, or perhaps he is simply recounting some of the myriad possible forms a city might take.