The second volume in James Blish's SF classic CITIES IN FLIGHT
Science has come to humanity's rescue with two crucial discoveries - antigravity devices that enable whole cities to be lifted from the Earth to become giant spaceships, and longevity drugs that allow their inhabitants to live for thousands of years - lead to the establishment of a unique Galactic empire.
Now, the earth's cities are able to abandon the worn-out homeworld for a new life, a new future. But what will they find as the hurtle off into the depths of space . . .
James Blish (1921-75) studied microbiology at Rutgers and then served as a medical laboratory technician in the US army during the Second World War. Among his best known books are Cities in Flight, A Case of Conscience, for which he won the Hugo in 1959 for Best Novel, Doctor Mirabilis, Black Easter and The Day After Judgement.