City Planet



""Coruscant… the capital of the Republic… the entire planet is one big city.""

- Ric Olié, Star Wars: The Phantom Menace

A City Planet is a Sub-Trope of Single Biome Planet and Mega City, in which said biome is said city. In other words, this is what happens when someone takes Planetville a little too literally: there is only one "city" on the planet, and it covers the entire planet.

Sometimes referred to as a planet city, world city (However, world city has also been used to mean other things), completely urbanized world, omniopolis / omnopolis, or ecumenopolis. While most examples are recent, the concept dates as far back as the nineteenth century work of Thomas Lake Harris, and the term "City Planet" dates at least as far back as the first draft of the script for Star Wars: A New Hope.

This trope occurs as the apparent result of a civilization, presumably over centuries of expansion, converting the entire surface of a world into one vast city. To be sure, many City Planets are divided into "administrative sectors" or other such local government institutions, but for all practical purposes, it's all the same city. Generally, this trope implies that for all practical purposes, the only biome of importance on the planet is urban jungle. Taken to an extreme, it may be implied the locals even paved over volcanoes and oceans in the process of creating the City Planet.

In works not all the way to the less realistic end of Mohs Scale of Science Fiction Hardness or the Sliding Scale of Realistic Versus Fantastic, such a world can present a Mega City - sized ball of Fridge Logic. Perhaps most importantly, how do people eat if there is no farmland? Often it's simply handwaved, but other times it's revealed that:
 * The local Starfish Aliens don't need food as we might understand it.
 * Food and other supplies have to be imported from elsewhere at great expense.
 * Much of the "city" actually consists of vast recycling, processing, manufacturing, etc., plants where everything people need (including food) is made or grown to order in highly controlled environments.

Because Sci-Fi Writers Have No Sense of Scale, City Planets tend to have implausibly low populations. An Earth-sized planet with the population density of Manhattan would have 14 trillion people, while a world covered with miles-high buildings would be far denser than that. But it's rare to see a planet with more than a trillion inhabitants. However, this assumes a near-universal population density throughout the planet and no large, minimally populated areas of automated processing for the population (as the third option mentioned above might imply).

Alternately, the trope will be subverted, introducing the audience to a seemingly endless city, and only later revealing that there are, in fact, vast areas of truly rural or wilderness areas remaining, the locals just don't like to talk about it.

Another Subversion can be that the city, despite covering an entire world, is no bigger than an "ordinary" city - because the planet is so small. In the past, such stories seemed more realistic than they do today; however, many serious hard - Sci Fi tales involve colonizing an asteroid or a city - sized space station. In recent decades, computer image manipulation technology has resulted in these occasionally showing up in video games or humorous images.

Finally, in some settings, a city occupies not a planet, but an entire plane of existence, a layer of a Layered World, or other planet - like... thing.

Anime & Manga

 * Tsutomu Nihei's Blame! is set in a City Planet that is implied to have long since consumed the solar system with its sheer enormity.
 * In Transformers Cybertron, over thousands of years of relentless construction, Gigantion has become several massive layers of city surrounding an Earth-like inner planet.

Comic Books

 * From DC Comics Jack Kirby's Fourth World series, Apokolips.
 * The concept is taken even further with The Hub in Transformers Generation 2 a vast physically connected network of Cybertron-type worlds that serves as the centre for power of the Cybertronian Empire.
 * The titular planet in Alejandro Jodorowsky's Megalex.
 * British 1980's science fiction comic Starblazer.
 * Issue 28 "Last Man on Earth". The Wheel was the fifth planet of Alpha Centauri. It was a planet-city ruled by a dictatorial AI computer.
 * Issue 29 "The Moonstealers". The planet Joaphat is covered entirely by a gigantic city with no areas of countryside.
 * Issue 59 "Starseeker Squad". The planet Bessel has an Earth city/colony that covers the entire planet.
 * Issue 64 "The Exterminator". Vanderdecken is a vast, ancient city-planet. Although this mysterious world is millions of years old, everything on it is in perfect operating condition.
 * Issue 208 "Planet of the Dead". The planet Vegas Prime is entirely covered in all manner of vice dens.

Film

 * Star Wars has Coruscant, the capital of the Galactic Republic. Other, lesser-known planets and moons also fit the bill, such as Nar Shaddaa.
 * In The Hutt Gambit, Han Solo notes that the uppermost levels of Nar Shaddaa look like the lowermost levels of Coruscant. He promptly resolves NEVER to visit the lowermost levels of Nar Shaddaa.
 * In Star Trek: First Contact, Earth has become this under Borg rule in an alternate timeline. Oddly enough the population consists of only 9 billion Borg even though the planet's entire surface seems to have been completely urbanized and technified. The planet might be one huge automated factory.

Literature

 * In Isaac Asimov's novels:
 * Trantor, capital of the Galactic Empire, is apparently completely covered by urban areas by the time of the Foundation series. Until it's sacked and looted into an agrarian world once the Empire falls.
 * In the prequel Prelude to Foundation, it is revealed that the planet is divided into approximately 800 domed cities, each with their own subcultures, with some open space in-between used for transportation, communication, cooling towers, etc. Trantor consumes most of the exports from a number of neighboring systems. (Prelude can be considered Asimov's attempt to reconstruct this trope.)
 * In his robot novels, Earth has become a planet of underground or domed "Cities". There's still wilderness outside, but very few people ever go there, so from the protagonists' point of view, they live on a City Planet.
 * In Larry Niven's novels:
 * The Puppeteer Homeworld. The Puppeteers terraformed at least four other worlds to farmland to ensure their food supply. Rather than abandon it, the Puppeteers converted all five into immense spacecraft.
 * Andre Norton's Uncharted Stars has a planet completely covered by city.
 * Bill The Galactic Hero by Harry Harrison features a world-covering city, Helior. While visiting, Bill suffers a grievous mishap: the map of the city chained to his arm is stolen leaving him one of the desperate Unplanned, with no hope of ever discovering where he is or where he needs to be.
 * It's worse than that. Losing a map is a crime on Helior. If you're caught without one, you're arrested.
 * It's pointed out that Helior imports all its food from agricultural planets in exchange for fecal waste to use as fertilizer. Apparently, they use the same transport ships for both. Bill also finds and nearly joins the organization responsible for waste disposal and recycling. They're desperately trying to find ways of re-using the stuff people throw away or, at least, prevent people from throwing away things, like plastic coffee cups that turn into music discs when they're empty.
 * Sheri S. Tepper has a novel called Beauty, in which the Earth has had all its wilderness wiped out, followed by any and all crop growing facilities.
 * And in Shadow's End, the governing planet of an entire solar system is a City Planet.
 * In Ecumenopolis, author, architect, and urban planner Constantinos A. Doxiadis suggests the Earth's fate is to a mild version of this, with rural and wilderness areas reduced to islands between the interconnecting "bridges" and "nodes" of a single city.
 * The Worthing Saga shows in passing how one of these came to be. The short story "Skipping Stones" begins on a world that's heavily developed, but is still famous for its wildlife, particularly its "whiplash trees" that bend all the way to the ground in windstorms. As the skyscrapers go up, the trees go extinct, and eventually all the planet has become the "Capitol" that is the focus of later stories.
 * In Emma Clayton's The Roar, "The Upper Half of the World".
 * From Dan Simmons' Hyperion Cantos, Tau Ceti Center and Renaissance Vector. Simmons at first explains away the food problem by means of the interstellar Portal Network (the farcasters) that make the transport of food from offworld a trivial matter (this same technology, after all, allows you to have a single house on twenty-plus worlds—if you're rich). After the network disappears, Tau Ceti Center collapses and becomes entirely deserted, while Renaissance Vector is able to hold on due to the existence of another planet with good agricultural land, Renaissance Minor, in the same star system.
 * The Star Wars Expanded Universe includes at least eighteen of these planets. Each has populations in the trillions and requires several nearby planets to support it. A complete list can be found here.

Live Action TV

 * Doctor Who features a whole-world library.

Tabletop Games

 * From Warhammer 40,000:
 * Holy Terra.
 * The Hive Worlds, though they're actually not a single city, but consist of "hives" (where the population is concentrated) dotting inhospitable (dangerously wild or wasteland) terrains.
 * Also, the Forge Worlds, although in this case the entire planetary surface consists of a single factory.
 * Necron Tomb Worlds
 * Dying Earth RPG supplement Turjan's Tome of Beauty and Horror. The planet of Merchdilan is entirely devoted to business/commerce and entirely covered by city.
 * In Dragonstar, Draconis Prime.
 * From Anachronox, Sunder.

Video Games

 * Emperor of the Fading Suns has "Megacity" type of planets, used for Byzantium Secundus and Leagueheim. However, they are not scoured of everything natural - "arid grass" hexes are replaced with concrete, "mountain" and "tree" layers with building, but some areas remain as green and/or potentially arable as they would be on Earth.
 * Total Annihilation: Subverted, Core Prime is a giant computer containing the conscience of the whole population and the entire Core culture.
 * From Freelancer, the planets Manhattan, New Berlin, New Tokyo and New London.
 * StarCraft also features several.
 * From Meteos, the oddly-shaped world of Grannest.
 * Zerard from Rogue Galaxy.

Webcomics

 * Irregular Webcomic spends a number of Star Wars strips deconstructing the idea, such as food, sewage, power, heat output, space, other sorts of atmosphere pollution and cooling. Unsurprisingly, Darths and Droids also touches on the issue.

Multimedia

 * Cybertron in Transformers, a machine world from core to surface. Except in Beast Machines.

Film

 * The city of Dark City is a rather unique example - it is a City Planet only because it's a world unto itself.

Literature

 * Isaac Asimov has a story called The Strikebreaker about a hundred mile asteroid with a colony - barely started, but already with a fifty thousand people population, fully self sufficient. The story is centered around the supply problem - the man responsible for recycling the waste decides to go on a strike.

Video Games

 * The Baby Planets from the second Ratchet and Clank game.

Comics

 * Asgard from The Mighty Thor, as well as its movie counterpart, is a city that encompasses another plane of existence.

Literature

 * In The Concentration City by J. G. Ballard, the densely crowded residents can't find an end to the upper and lower floors of the buildings they live in. Train rides out of the city end with you coming back in. Coming back on the same day, the exact same time, as your departure. This is a city that has swallowed everything.

Tabletop Games

 * In Dungeons & Dragons/ Planescape
 * Sigil, or City of Doors, occupies the inner surface of a torus-shaped world.
 * Dis, the second layer of Hell, is a single, vast city.
 * Mechanus, the heaven for Lawful Neutral beings, consists largely of clockwork structures. Some of the gears alone are said to be the size of small continents, and many have buildings and/or various terrains on top of them.
 * Magic: The Gathering has a high fantasy version of this in Ravnica. The city covers the primary planet in one plane of an infinite Multiverse.
 * The illustrations on some of the Basic Land cards are particularly impressive, depicting urban Forests, Swamps, and Plains.