Mega City

"I was born in apartment block Seven of Nine, in the Tertiary Adjunct of Unimatrix Zero One," replied Annika in a clipped tone. "An arcology so large it contained the entire population of Greater Germany — the builders had to fill in the North Sea just to provide parking space."

— Plan 7 of 9 from Outer Space

A city whose population and physical size are massive, not just in raw numbers but in density. The actual size can depend on the average city size of the setting, but for modern or Science Fiction settings, you can assume that the number of citizens goes into the hundreds of millions or even billions.

Depending on the setting you can expect to see a lot of tall buildings, endless suburbs and futuristic ways to get around. If you are lucky to get an author who is good at worldbuilding, they may have even thought of how the megacity handles challenges with providing food and water for all the inhabitants as well as the environment (human waste, garbage and pollution) so many people naturally generate. If you are unlucky however, the author may depict unrealistic situations, like the heroes finding themselves alone in public at times and places where that should be impossible given the population density.

The Mega City will probably be the capital or Hub City, and if it's not a Merchant City, there'll definitely be a Bazaar of the Bizarre, where everything legal and illegal is available, if you know where to look and who to ask.

Mega City is Super-Trope to City Planet, where a futuristic city encompasses the entire planet; Skyscraper City, where the city has grown very tall (may or may not overlap with Layered Metropolis); and Hive City, where the city's growth has become dense and layered enough to transform it into a near-solid mass of architecture.

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Examples:

Anime & Manga

• Blame!: The City is humongous. The tie-in art book says it's a growing Dyson Sphere the size of Jupiter's orbit. Tsutomu Nihei breathes this trope, hell, there's an artbook of his that consists solely of this. It's beautiful, and understandable coming from a guy who happened to study architecture several years.
• Welcome to The Space Show: The Space Federation base covers most of the dark side of the Moon and rises into space but somehow hasn't been noticed by humanity.

Comic Books

• Doctor Who Magazine:
  • The Betrothal of Sontar shows that the planet Sontar has continents covered by cities.
  • In "Mancopolis", the eponymous 25th century version of Manchester occupies 500 square miles (slightly larger than present day Greater Manchester, which is not a fully urbanised area) crammed full of skyscrapers linked by walkways, and tall enough to be visible from the wastelands of The Midlands.
• Judge Dredd: The world is divided into these kinds of cities. Much of the world outside the Mega Cities was destroyed in the Atomic War of 2070, leaving the metropoles as the last centers of advanced civilization due to their missile shields having withstood the worst nuclear attacks. Dredd's home city of Mega City One grew from BosWash until it covered the entire eastern seaboard. In fact, the whole point of the Apocalypse War arc was to trim its sheer size down, as it had become too big.
• Legion of Super-Heroes: By the 30th Century, Superman’s hometown of Metropolis has expanded to the point it has engulfed New York, Gotham City, and Boston.
• Magnus Robot Fighter: The city of NorthAm covers all of North America.
• The Mighty Thor #372, part of a storyline involving Time Travel, says that in the future the entire east coast of the USA will be covered by the megacity of Brooklynopolis (which will be policed by the oddly-familiar Justice Peace).
• Sinister Dexter: Downlode stretches from northern Spain to west Poland.
• Transmetropolitan: It's unclear where the City is or just how big it is, but some stories imply it to stretch from New York to the Great Lakes, and it's massive enough to be a deciding factor in elections.

Fan Works

• Coreline: The city of Los Angeles, California has become one of these in the aftermath of the Vanishing. The police headquarters alone has become a multi-mile-high heavily-armored Arcology. The old Los Angeles became an Underground City wherein all kind of Cyberpunk tropes are done willy-nilly, and it's essentially become the town's Red Light District.

Films — Live-Action

• The Matrix: The pre-war human cities "spanned hundreds of miles" and needed armies of robots to maintain themselves. It's implied that the entirety of civilization within the Matrix is one of these, dubbed "the city" for lack of need for a more specific name.

Literature

• The Big Kiev Technician:
  • Big Kiev is roughly 600 miles in diameter. It takes nine hours on a train to get from the Black Sea in the southern part of town to the Center (where our Kiev, Ukraine, is located). One of the old cities absorbed into Big Kiev is L'viv, which in real life is at the far end of Poland from Kiev. Only canned goods are available in the Center due to lack of farmland or cattle so far from the edge, unless you're willing to spend a fortune on fresh meat and fruit.
  • Big Moscow is mentioned to be even larger, although younger. A military conflict is mentioned to have happened in the past between Big Moscow and Big Berlin.
  • This can be partially explained by cities apparently growing on their own, as a jungle would. This fits into the overall theme of all machines in this world being alive. Apparently, the major cities have been slowly growing for the past 300,000 years in the novel's timeline.
• Book of the New Sun: It takes days to travel from Nessus' center to the outskirts. Large portions of it, however, are in ruins and inhabited by cannibals.
• In the Bounders series, most Earthlings live in gigantic cities hundreds of miles across, with names like East Americana and Amazonas.
• The Caves of Steel: All of Earth's population lives in eight hundred arcologies known as "Cities". The average population of each City is eleven point two million. The governments of three large cities (New York, Philadelphia and Washington) are considering merging into one single Mega Mega City, but the logistics of maintaining and governing such a large conglomerate have so far prevented any action on the plan.
• Discworld: While Ankh-Morpork only has a million inhabitants, it is still the biggest city in the setting. In The Fifth Elephant, Carrot points out that it's actually the largest dwarf city, having more dwarfs than any purely dwarf city. (This isn't as far-fetched as it may seem — a Real Life example is the city of São Paulo, whose Italian community is larger than any city in Italy itself.)
• The History of the Galaxy: Earth cities are mentioned to have become these with populations of major cities approaching twenty billion each. That's nearly triple the population of the entire world today in a single city. This is the main reason why President John Winston Hammer of the Earth Alliance sends a fleet to force the recently-discovered Lost Colonies into submission, so as to offload the extra population. By the time of the later novels, most of the population has moved to new colonies or died in the First Galactic War (the 30-year war with the colonies, which Earth ultimately loses) with only about 100 million people left on Earth. Most urban areas, now abandoned, are covered by lush jungles, and many surviving landmarks have been moved to other areas for preservation. After the war, the colonies emerge as the industrial, economic, and scientific power in human space, forming the Confederacy of Suns for mutual protection (Earth isn't included).
• The La Nague Federation: Earth (and some colonized planets) has several Megalops with stupidly huge buildings and nightmarish overpopulation. Food riots are not pleasant affairs.
• Poster Girl takes place in a Megacity formed in the American Northwest between Seattle and Portland.
• Sprawl Trilogy has the titular Sprawl, more officially known as BAMA, the Boston-Atlanta Metropolitan Axis, presumably an extension of the real Bos-Wash. Also notable for being almost completely covered by geodesic domes. Judging from descriptions in Neuromancer Chiba City and the other cities around Tokyo Bay also count.
• Super Minion: Fortress City is designed to hold the population of the entire western seaboard if need be. It's composed of fifteen concentric rings of eight sectors each, and each sector is big enough to need its own mayor and municipal law code.
• The 13 ½ Lives of Captain Bluebear: The Capital of the continent of Zamonia, Atlantis, has over 200 million inhabitants.
• Ward: The unnamed city of Earth Gimel, where most of the story takes place, is a megalopolis stretching roughly from what would be New York City in Earth Bet to Boston, but slightly offset to the northeast due to the oldest Earth Bet portal being located where Brockton Bay would be.

Live-Action TV

• Aftermath: Population Overload: Most of the population of North America becomes concentrated around the Great Lakes after a drought-induced mass migration, resulting in a massive mega city surrounding the lakes.

Radio

• Jack Flanders: At the start of "Dreams of Rio", all of North America has become one giant city, mostly devoted to selling Coca-Cola.

Tabletop Games

• Cyberpunk: One of the main locations is Night City, a massive, William Gibson-style Mega-City in California founded by Richard Night, a businessman who wanted to create the ideal city. It came pretty close to actually meeting that goal, but after Night was assassinated by a criminal gang, it steadily became an overpopulated Vice City. By the time of the video game, its regarded as one of the worst places in the United States to live.
• Electric Bastionland takes place in the city of Bastion — a city that's not only massive, but constantly shifts its own surreal architecture, to the point where accurately mapping it out proves to be impossible. Hidden in many nooks and crannies of the city is countless treasure, which is what the players are tasked with looking for.
• Shadowrun has sprawls and metroplexes, gigantic cities covering every inch of the game's world that is likely to matter, with a few areas reclaimed by nature ending up polluted beyond the point of being habitable.
• SLA Industries: Mort City is roughly the size of Eurasia.
• Warhammer 40,000: Many Imperial worlds are dominated by "hive cities", mountains of metal housing millions (if not billions) of inhabitants and dependent on imported food and water from neighboring Agri Worlds. They tend to be highly stratified societies, with the administrators and wealthiest citizens living comfortably in the Spire, while gangs, mutants, and worse struggle to survive in the dark and decaying Underhive. Many of the Imperium's officially-designated City Planets aren't actually covered entirely by urbanization, but are rather dotted with hive cities separated by the resulting Polluted Wastelands.

Video Games

• The Last City from Destiny, a huge sprawling metropolis that serves as the Last Bastion of human civilization, with a population in the millions and ever-growing. Its size is never given, but it looks to be about as big as the Greater Tokyo Area at least.
• Dreamfall Chapters: Europolis is a dystopian Stark city covering most of Central and Western Europe.
• Final Fantasy VII: Midgar is a massive Layered Metropolis so gigantic that each of its nine districts is practically a city unto itself. It's so big that it takes tapping into The Lifestream to meet its insane power demands and has to leech so much energy from it that the area surrounding the city is a barren, lifeless wasteland.
• F-Zero GX: Mute City, formerly called New York City (according to the anime F-Zero: GP Legend), has grown to a population of over two billion people and aliens.
• Granblue Fantasy has the Erste Empire's capital island, Agastia, which is a gigantic sprawling city and military complex that occupies the entire island with little greenery to be seen.
• Guild Wars Factions: The Hong Kong-like Kaineng City covers about a good third of the continent of Cantha.
• Halo 2 and Halo 3: ODST's supplemental materials establish that the African port city of Mombasa experienced a massive period of growth and prosperity after a Space Elevator was constructed there in 2302. By the time the games begin in 2552, the municipal sprawl of "New Mombasa" has grown to encompass everything within a 74-kilometer radius of the original city. Halo 2 features several levels set in the city as it's invaded by aliens, while ODST is set entirely within it, following a squad of ordinary soldiers trying to escape the city after the battle is lost.
• The City from Lobotomy Corporation, Library of Ruina and Limbus Company is the size of at least a continent and has a population in the billions — most of which live in sprawling slums called 'Backstreets', while the privileged few live in (relatively) safe zones called Nests controlled by one of several Megacorporations.
• Mass Effect 3: One of the playable locations is a city formed from the unification of Vancouver and Seattle.
• Mega City Police has its titular Mega City, which encompasses every single possible trope concering a Mega City that there is. It's an Urban Hellscape populated by Cyberpunk gangs, it's ruled over by an amoral MegaCorp and its police force is unnecessarily brutal and violent.
• SimCity: One of the ultimate goals in the games is to reach as high a population as possible. In the original game, reaching a population of 100,000 would upgrade your city into a Metropolis. Reaching 500,000 citizens meant that your city be classified as a Megalopolis.
• XCOM Apocalypse: According to the Backstory, Mega-Primus is actually the prototype of the concept designed to consolidate the remaining living space on the planet following the aversion of No Endor Holocaust at the end of Terror from the Deep.

Webcomics

• Gunnerkrigg Court: The court itself has gigantic proportions; its full size is not shown, but it's too big to leave on foot, appears as an endless series of streets and buildings stretching to the horizon, and contains seemingly no end of residential districts, industrial areas, and secret government facilities and holding areas buried in its sprawl.
• Kill Six Billion Demons is mostly set within Throne, an utterly massive metropolis in the center of the multiverse that was once Home of the Gods. Following the death of said gods in a huge war, it is now inhabited by an ever-ballooning population of humans and aliens from numerous different worlds, and tyrannically ruled by the Seven, the only gods to survive the Multiversal War.
• Schlock Mercenary: Most of Earth's population lives in such megacities, averaging out at populations of three to five billion each, made of clusters of arcologies. Despite a planetary population of nearly 200 billion in the opening days of the thirty-first century, extensive use of such high towers means that they only take up about 10% of the Earth's surface.
• Shifters: The comic takes place in Shade City a Mega City that encompasses a vast amount of territory in the Pacific Northwest.

Web Original

• Dynamo Dream: Shade is a city the size of an entire state; it may be the last city on Earth, judging from the complete lack of lights on the night side of the planet.

Western Animation

• Avatar: The Last Airbender: The Outer Wall of Ba Sing Se seems to encompass nearly 10% of the land area of the largest continent on its planet, and its population is equally gigantic, especially in comparison to those of the entire Air Nomad and Water Tribe civilizations.
• Phantom 2040: Metropia is a self-governing city-state of thirty-two million inhabitants — that's over 10% of the entire population of America at the time it was made.
• Transformers: In most series, Cybertron is about as large as the Earth, all the way up to the size of Saturn in some series. Despite this, most of its cities aren't just visible from orbit, they're so large they visibly alter the planet's silhouette. Population tends to be smaller than one might think, given that the average native is around 20-30 feet tall and the infrastructure is accordingly scaled up.

Real Life

• The proper term to describe cities — more specifically, broad-stroke regions — that have reached extreme levels of population and urban development is megalopolis. A megacity, on the other hand, is typically defined as "a metropolitan area with a total population in excess of ten million people". While there is considerable overlap between the two terms, a crucial difference is that a megacity can be a single metropolis, while a true megalopolis comprises a chain of highly interlinked metropolises. The following examples listed below all qualify as megalopolises, as most of them are a chain of metropolitan areas that are so closely connected to each other that they have begun to overlap.
• The metropolitan area of Jakarta, the capital of Indonesia, houses 30 million people, slightly less than the total population of the country's southwestern neighbor, Malaysia (32 million). And you can't dismiss Malaysia as a small country either; 127,724 square miles, compared to Metro Jakarta's 6,615 square miles. Were it a country in its own right, it would be the 45th most populous in the world.
• There are about as many people in Tokyo and neighboring cities as there are people in Canada, which makes the Tokyo Is the Center of the Universe trope feel juuuuust a little bit Justified. If Tokyo were a separate country, it would be the 34th most populous in the world, after Poland.
  • Speaking of Canada, the Greater Toronto Area (which includes the City of Toronto as well as several other nearby towns and cities of varying sizes) contains over 6 million people and occupies an area of over 7,000 square kilometres. This alone represents about one-sixth of the entire population of Canada. With that said, it falls short of the usual definition of a mega city as a metropolitan area with more than 10 million people.
• Manila's situation is zig-zagged: while the city proper (Manila itself and the city that contains at least the presidential residence) has at least 1.8 million people, the other cities comprising the region makes the Metro Manila area, called the National Capital Region, large enough for the area to be considered this trope, with at least 13 million for the region and 24 million if the surrounding suburbs outside the National Capital Region are added. As of 2024, its population is as large as Taiwan's.
• Keihanshin (Kyoto-Osaka-Kobe) is no slouch either. The figure varies depending on the method, but it is somewhere around 17-20 million people. Unlike other metropolitan regions, however, Keihanshin was unique in that Kyoto and Osaka were (and to some extent, still are) separate cities with separate civic cultures for most of Japan's history. It was only with the rise of modern transport in the early-to-mid 20th Century that the two cities started to form an integrated metropolitan region.
• Although it may not seem like much compared to other entries in this list, London was probably the first modern metropolis with a population of 6.7 million in the 1900s. It is still one and the largest among European cities, with 14 million people living in the London commuter belt which includes the Greater London area. Said population is also relatively low for the amount of space that London occupies because the city has a relatively small number of true skyscrapers: The ground is so marshy that for most of the city's history, it was cheaper and easier to build out rather than up.
• Speaking of European cities, Paris and the surrounding Île-de-France region also counts. 12 million, or approximately one-fifth of the French population, live in the region, making it Europe's fourth largest metropolitan area.
• By some definitions, the "Blue Banana", also known as the "European Megalopolis" is a single interlinked megalopolis that stretches from Liverpool in north-west England to Milan in Italy. The estimated population is over 110 million people, or around a fifth of the entire continent. Which rather puts Moscow's claims to shame...
• Moscow, by the way, is the largest Mega City in Europe. The most conservative reckoning of the megalopolis' population is 16.8 million people, not counting unregistered, transient and illegal residents; with them, it could easily top 20 million. The "official" city without suburbs and satellites has 12 million people.
• İstanbul's metropolitan area, with almost 15 million the second largest in Europe, actually dwarfs the total population of its host country's Balkan neighbors, Greece and Bulgaria, which have 10 and 7 million, respectively. Even if you subtract the Asian side of the city, it leaves around 9.5+ million intact, still larger than Bulgaria.
• In the US (and other places), urban sprawl has started expanding cities to the point where they run together. For instance:
  • The first was known originally as BosWash (sometimes New BosNYWash given New York City is a big percentage of the people), a near contiguous mass of cities and suburbs running from Boston to Washington, D.C.. Currently the cities in this area have yet to fully coalesce, although New York City/North Jersey/Fairfield County (CT) and Philadelphia/Camden (NJ) are close, as are Boston, Worcester (MA), and Providence (RI). ^note The fastest growing area in Massachusetts is the corridor of outer suburbs between Route 128 and I-495 known collectively as MetroWest, while Route 1 between Boston and Providence is essentially one long commercial strip anchored by the Automile in Norwood (just off 128) and Gillette Stadium in Foxboro, somewhere in the middle. Likewise, the DC area spills over into northern Virginia and Maryland, to the point of sometimes being grouped with Baltimore.
  • The Los Angeles metropolitan area is currently the largest (in terms of area) metropolitan area in the United States and the second most populous, with more than 15 million residents.
    • The coastline of Southern California is essentially this. Driving on Interstate 5 from the US-Mexico border at San Diego all the way to the Interstate 210 interchange in north San Fernando is about 140 miles of urban scenery. The total distance is really about 160 miles, but 20 of that goes through a nature preserve in Camp Pendleton.
  • The San Francisco Bay Area (in California), depending on where exactly you draw the boundaries, comprises up to 8.5 million people and is potentially the 5th-largest metropolis in the United States — after the Los Angeles area — with a steadily growing population from immigration into the region. It's a well-networked mesh of cities, suburbs, and large towns that surround the SF Bay, and continue to extend outward from there. Notably, San Francisco proper has remained stagnant over the years with a population hovering around 800,000 due to being the tip of the San Francisco Peninsula and not having much undeveloped land left, while other cities continue to grow — San Jose is the most populous city in Northern California and continues to grow to 1,000,000 and beyond due to sitting on about 180 square miles of land, a good chunk of which is still undeveloped, as opposed to SF's 46 square miles (often appromixated colloquially as "7 x 7").
  • America's "Second City", Chicago, has the number 3 spot in terms of metropolitan population, behind NewYorkCity and LosAngeles, sitting pretty at almost 10 million people. It is also grouped into what is called the "Great Lakes Megalopolis", which is effectively the Midwest's answer to BosWash and is even larger, being home to 59 million people, which makes it the largest megalopolis in the Western Hemisphere. At its most generous extent, it is said to run from the Twin Cities in Minnesota to Quebec City, Quebec. However, the megalopolis is not necessarily a megacity in the sense of having overlapping urban environments, and is instead more a commonly linked economic zone and transportation corridor that surrounds the Great Lakes, and the vast majority of it is rural and suburban. However, Chicago and its neighbor Milwaukee are still fairly close to the concept, with intermittent cities like Kenosha bridging their two urban areas.
  • South Florida (the metropolitan area based around Miami) is a continuous strip of connected cities running 110 miles, though never more than 20 miles wide. It's the longest unbroken strip of urbanization in the United States and is home to over 5 million people.
  • The DFW Metroplex of Texas has about 6.5 million inhabitants living in well over 200 individual towns and cities, the largest metropolitan area in the Southern United States. It is generally split between two main divisions, the Dallas-Plano-Irving group and the Fort Worth-Arlington group, but they're all close enough that it hardly matters.
• Mexico City. The city proper has about 9 million, but the metropolitan area (depending on who asks) has somewhere between 20 and 22 million people. That's more than the entire population of some Latin American countries like Chile.
• And that's not even the largest conurbation in the Americas. That honor belongs to São Paulo...
  • The municipality (city proper) has over 12 million.
  • The legally defined metropolitan area, known by the Portuguese abbreviation RMSP, has over 23 million.
  • In turn, this entity is part of the São Paulo Macrometropolis, or Expanded Metropolitan Complex, which adds four metropolitan areas that border the RMSP and three additional nearby regions. This area is estimated to have 36 million.
• The Kowloon Walled City in Hong Kong is an interesting example: while relatively small in comparison to other examples, it occupies a tiny conclave of Chinese-owned territory in colonial Hong Kong, measuring a scant six-acre area in which it could legally be built. Because of its tiny border, the city expanded upwards rather than outwards, and its architecture was very dense.
• Basically any city and conurbation in China People's Republic is a megacity by default, simply due to the humongous population of the country. Due to this aforementioned population, though, China also averts Tokyo Is the Center of the Universe, as the 1.3 billion+ head count can't physically crowd themselves in one corner, but instead have to spread out of the land area.
  • There are very large cities in China such as Shanghai (20 million) and Beijing (17 million), as well as a number of large cities in the Pearl River Delta such as Shenzhen (12 million) and Guangzhou (16 million). Take note that the delta is also the location of Hong Kong (7 million) and Macau (650,000, but its status as China's Las Vegas means that the headcount swells up every other time), so the locals of the delta really don't have to go anywhere else in the country to find services. And yes, it may one day merge to form the largest mega city in the world.
  • Foreign media often neglects the differences between a city proper and a City-Prefecture unitary authority, resulting in plain wrong statements. The prefecture is often much larger and populous than the city proper of the same name, comparable to a small European country.
    • When Chaohu prefecture (population 4 million) was dissolved, there were news stories claiming a city as large as Los Angeles suddenly disappeared from the map. The Chaohu city proper (not really annexed but now a county-level city belonging to Hefei prefecture) has a population of about 800,000.
    • "World's most populous" Chongqing Municipality is a merger of 4 former prefectures, has a population of 29 million, and is larger than Scotland. The real city proper of Chongqing has 8 million residents.
    • "World's biggest by land area" Nagqu, Tibet is even larger than entire Sweden. This city-prefecture contains several counties and other cities (as the norm); the real city proper (Seni District) occupies 3.5% of the total land, and is not big by Chinese standards.
    • The above figures for Beijing, Shanghai, Guangzhou, Shenzhen are similarly inflated, as a prefecture may have many rural counties. Nonetheless, their urban areas are large on their own. If you count people regularly residing (as opposed to only those who have Hukou, which is official permanent residence and entitles you to full social benefits of such a city), then Beijing and Shanghai already have over 20 million people in the city proper (as of 2014).
    • Shanghai Metro has crossed the Shanghai-Jiangsu province border with stations in Huaqiao, Suzhou Prefecture, Jiangsu (not Suzhou city proper, but easily reached by Suzhou city bus). Downtown Suzhou is 80km away from Downtown Shanghai.
    • As of February 2014, there are no counties left in Southern Jiangsu and only one in Shanghai (the distant Chongming Island). All such areas, home to over 53 million people, are city districts or county-level cities, although many suburbs are not meant to be completely urbanized. This does not even include cities on the north bank of the Yangtze (Central Jiangsu) or further south (Northern Zhejiang) where urban areas are not large enough to touch each other but still heavily connected via numerous expressways (not to mention high-speed rail).
    • Guangzhou have effectively integrated neighboring Foshan (which is 20 km away from downtown Guangzhou, administratively still a separate prefecture-city), and the larger Pearl River Delta, not only Shenzhen, is also urbanized and interconnected similar to above. (It even includes Hong Kong despite border controls, with Shenzhen Metro and Hong Kong MTR connecting at checkpoints.)
• Mumbai and Delhi/New Delhi in India have populations of over 20 million and over 15 million respectively.
• There are the two largest metropolitan cities of Africa: Cairo (20 million people when you include Giza and the suburbs, which you should) and Lagos (12 million).
• Seoul is also this. In fact, half of the population of South Korea resides in the Seoul Capital Area (25.5 out of 51 million) with 10 million of them in Seoul, making it one of the largest metropolitan area in terms of population. Its semi-affectionate nickname as the "Republic of Seoul" isn't completely unfounded when you consider that most of your extended family probably live somewhere in the area. It's been said that "Seoul was not simply Korea's largest town; It was Korea."
  • The Busan-Ulsan-Gyeongsangnamdo metropolitan area with Busan at the center isn't as large as the Seoul metropolitan area, but it still houses 8 million people, making it the second largest metropolitan area in South Korea.
• Another East Asian state, the de facto nation Taiwan, also has one, the Taipei metropolitan area with 7 to 9.2 million people. Taipei itself is actually two cities, the capital city Taipei with a population of 2.7 million and New Taipei that completely surrounds it and has a population of 4 million. New Taipei used to be "Taipei County", but as it had become completely urbanized it was designated a city in its own right in 2010. The variance in the population for the metro area as a whole depends on whether Taoyuan, (population 2.2 million) is included in the Taipei metropolitan area. The larger definition of the metro area contains nearly 40% of Taiwan's total population of 23.7 million (as of 2019).
• The fertile valleys of the Nile, Tigris, and Euphrates rivers allowed Babylon, Thebes, and Alexandria to each become a Mega City at different points in history, at least by the standards of their time. Later, grain brought in from all over the Mediterranean (including the aforementioned Nile valley) allowed Ancient Rome to do so.

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