Caves of Steel, by Isaac Asimov

The Caves of Steel is a 1953 science fiction mystery novel by Isaac Asimov. Set in a future Earth where eight billion people live in crowded underground cities, New York City detective Elijah Baley must partner with a humanoid robot, R. Daneel Olivaw, to solve the murder of a Spacer ambassador. The mystery explores social tensions between anti-robot Earthmen ("Medievalists") and the technologically advanced Spacers.