Often, they are powered by advanced energy sources. For example, in some stories, they use clean fusion energy. This provides a large amount of power without the pollution of traditional fuels. Another common power source is some form of crystal - based energy. These crystals can be mined and harnessed to provide the necessary electricity for the city's functions, like keeping it afloat and powering all the buildings and machinery within it.
One of the well - known floating cities in science fiction is Cloud City in 'Star Wars'. It's a gas mining colony that floats in the atmosphere of the planet Bespin. Another is Columbia from 'BioShock Infinite'. It's a beautiful but deeply troubled floating city in the sky. And there's also Zion from 'The Matrix Reloaded' and 'The Matrix Revolutions', which is a last human city deep underground, though not exactly a floating city in the traditional sense but has a similar sense of being an isolated and unique city in a fantastical setting.
One famous example of floating cities in fiction is Laputa from 'Gulliver's Travels'. It was a flying island, which represented a kind of advanced and mysterious civilization. The concept of floating cities and islands often symbolizes isolation, superiority or a different way of living. It can also be a place full of imagination, like a utopia or dystopia depending on the story.
It could be about exploring various aspects of science fiction settings within a large number of cities. Maybe it involves different technological advancements, social structures, or alien encounters in those cities.
Space cities in science fiction are different from Earth cities mainly in terms of environment. Earth cities are built on solid ground with a breathable atmosphere naturally. But space cities need artificial gravity and controlled environments. Also, space cities are more likely to be isolated from other places.
Atlantis is sometimes depicted as a floating island in some fictional interpretations. It was a very advanced civilization that eventually sank. In the 'BioShock' game series, there are floating cities called Rapture. Rapture was built underwater initially as a utopia for the best and brightest, but then things went horribly wrong.
In some science fiction, cities on the Sun are depicted as these glittering, energy - based constructs. They might be shown as using the Sun's intense energy in ways we can't even fathom, like powering some sort of super - advanced technology. Writers often use the idea to represent the height of technological achievement and the exploration of the most extreme environments.