“This is from Kim Stanley Robinson’s short story Mercurial, which isn’t really about the city at all although it plays a large part. It’s a detective story about an art collector on Mercury. With this city, resistance to the motive force is used to generate large amounts of electricity. The city slides round the entire planet, slowly, again and again. They sell the electricity to other planets.”
Slide 4 of 50 (Sci-fi I like, Fictional Futures, Goldsmiths)