I recently read Invisible Cities by Italo Calvino.
Written mostly in prose, the book is built around imaginary discussions between Kublai Kahn and Marco Polo who reports to the emperor on his travels to 55 imaginary cities.
“The book, because of its approach to the imaginative potentialities of cities, has been used by architects and artists to visualize how cities can be, their secret folds, where the human imagination is not necessarily limited by the laws of physics or the limitations of modern urban theory. It offers an alternative approach to thinking about cities, how they are formed and how they function.” (source: wikipedia.org).
The stories are wonderful reminders of what cities can and could be. I think it should be required reading for all urban planners.