More vertical geography:
I've just moved into a new apartment. I live on the upper floor of a converted house, and my friend SD lives on the ground floor. A chimney runs up one side of the house, and we each have a window which opens into the chimney.
The inside of the chimney is airy and well-lit, and lined with bright books. If SD ever happens to be by the window downstairs, or is looking for books in the chimney, I can attract his attention by waving a shiny pencil, and he will climb up the bookshelves to come and say hello.
Later on, while we're inside another building, there's a frightening episode when deep fissures open up in the ground, and angry vampires hurl human bodies back and forth. But the verticality is less pronounced during this episode, in that I'm not able to see very far into the fissures, and certainly not about to try climbing down them.