鋼鉄都市
This story is set within Asimov's "Foundation" universe, which also includes his earlier Susan Calvin positronic robot tales. It is clearly set centuries prior to the events of his novella "Mother Earth" and the novel "The Caves of Steel", during a period in which the Spacer worlds have yet to turn against the people of the Earth, and in which the U.S. Robots corporation is still active.