Floating cities and islands in fiction

In the treatise De Grandine et Tonitruis ("On Hail and Thunder", 815), Carolingian bishop Agobard of Lyon describes Magonia, a cloud realm populated by felonious aerial sailors.

It was primarily a fictional device that was intended to satirize far-fetched pseudo-scientific proposals: During the 1920s, science fiction author Hugo Gernsback speculated about floating cities of the future, suggesting that 10,000 years hence "the city the size of New York will float several miles above the surface of the earth, where the air is cleaner and purer and free from disease carrying bacteria."

To stay in the air, "four gigantic generators will shoot earthward electric rays which by reaction with the earth produce the force to keep the city aloft.

[7] In Isaac Asimov's story "Shah Guido G.", the hereditary Secretary-General of the United Nations ("Sekjen") is a tyrant who rules the Earth from a flying island called Atlantis.

[9] At an altitude of 50 km above the Venerean surface, the environment is the "most Earthlike in the solar system", according to Landis,[10] with a pressure of approximately 1 bar and temperatures ranging between 0–50 °C (32–122 °F).

Jupiter is not promising for habitation due to its high gravity, escape velocity and radiation, but the Solar System's other gas giants (Saturn, Uranus, and Neptune) may be more practical.

In 1978, the British Interplanetary Society's Project Daedalus envisioned floating factories in the atmospheres of Jupiter refining helium-3 to produce fuel for an interstellar probe.