![Cities in Flight Cities in Flight](https://books.azurecurve.co.uk/wp-content/uploads/2020/03/cities-in-flight.jpg)
James Blish's volume explores a future in which two crucial discoveries -- antigravity devices which enable whole cities to be lifted from the Earth to become giant spaceships, and longevity drugs which enable their inhabitants to live for thousands of years -- lead to the establishment of a unique Galactic empire.