What If Everyone Lived in Just One City

world population

Current estimates put the total world population at just over 7.7 billion. Despite there being more people alive now than have ever lived or died before, it seems like we’re actually pretty well spread out. The majority of people live in Asia – around 60% – while 16 percent live in Africa, 10 percent live in Europe, 8 percent in North America, 5.5% in South America, and only 0.5% in Australia and Oceania.

Today, however, 55% of the world’s population lives in urban areas, and that number is expected to increase to 68% by the year 2050 – meaning we’re not nearly as spread out as we think.

© Our World in Data

If that urbanisation trend continues, we should expect to see more and more large and extremely dense megacities developing in order to accommodate population growth. Now this got me thinking – what would it be like if everyone on earth lived in just one huge city? What would that city look like? How would we cope with it? And would it even be possible? Let’s find out.

The Smallest Possible Land Size to Accommodate World Population

First, lets find out how small a single city of the world’s population could be at a density that people could live with. Defining a city as a place with over 150,000 inhabitants, the world’s top three most densely populated cities are Dhaka in Bangladesh, Ebeye in the Marshall Islands, and Manila, the capital of the Philippines.

© Flickr/United Nations Photo, WSJ, and Bernhard Lang

Of these three, Dhaka has the highest total population at 14 million, and Ebeye covers the smallest area – but Manila’s density of 41,515 per km2 is the world’s highest, despite its relatively small population of 1.78 million. So if we were to try and fit the entire world’s population into a city of Manila’s density, that city would need a total area of 185,500 square kilometres – so roughly the size of Syria, or South Dakota.


Now that would be some city! But could we make it even denser?

The highest population density ever recorded was that of Kowloon Walled City in 1987, which was a Chinese military fort. It had a density of 1.25 million inhabitants per square kilometre. Here’s an illustrated cross-section that gives you some idea of its compactness.

© This Colossal

The settlement was demolished in 1993 after an arduous eviction process, but the legend of the absolute real-world limit for population density lives on.

So in order to fit the entire world’s population into a single city at that density, you would need an area not much larger than modern-day Palestine – 6,160 km2.

© Muslims in Calgary

The total area of Palestine is less than half the size of the Tokyo Metro area, which should give you some idea of just how tightly packed this megacity would have to be.

The Most Suitable Location to Build the Megacity

Now that we’ve figured out the smallest possible area of land that could feasibly house a city of the worlds population, lets now think about where we’re going to put it. There are plenty of factors to consider here: safety from environmental and ecological disasters, proximity to water and food sources, and ease of construction, to name a few.

The countries that are safest from natural disasters, according to EM-DAT – the international disaster database – are Estonia, Qatar, Bahrain, the UAE and Andorra. Unfortunately Andorra is far too small and mountainous, and the three middle-eastern countries don’t have enough nearby agricultural land.

© Wikimedia Commons/اللولب

Estonia, however, is a fairly flat country with over 669,000 hectares of arable land and plentiful access to water and electricity, as well as the rest of Europe and Asia. It’s also relatively safe from flooding, so we wouldn’t have to worry too much about the ice caps melting.

© PX Here

The climate is temperate and mild, characterised by warm summers and fairly severe winters – though cold winters would probably be the least of your worries if you were packed into six thousand kilometres squared with every other person on the planet, like some kind of titanic penguin colony. So, Estonia it is!

© Visit Estonia

The World Megacity: What Would It Look Like?

Now that we’ve chosen the location of our world megacity, it’s time to think about what it would look like. In this photo taken in 1989, Kowloon Walled City looks kind of like a dump.

© Business Insider

Its shabby, makeshift buildings were limited to 13 or 14 storeys in height, and even then sunlight was almost totally unable to reach street level. Some parts of the street used to have lights on even in the daytime. Our Estonian Megacity, however, would have no such height restrictions, so it would probably have quite a few enormous skyscrapers, further blocking light at street level. This illustrated cross-sections of the Walled City shows lush rooftop gardens – a primitive example of arcology.

© This Colossal

Arcology is a portmanteau of the words architecture and ecology, and describes the field of architectural design concerned with creating very densely populated, ecologically low-impact human habitats. A world megacity would need to employ the principles of arcology in order to maintain biodiversity and anything close to safe levels of air pollution. The overall result would probably consist of a variety of different structures. Although tightly-packed tenement structures would certainly dominate because of their efficient use of space.

Potential structures might also include presently conceptual buildings like the Shimizu TRY 2004 Mega-City Pyramid, which was designed to be coated in photovoltaic film to convert sunlight into electricity, and would also have made use of pond scum to generate power.


They could even look like the mighty X-Seed 4000 – the tallest and largest building ever conceptually designed. The architects of such a city would need to make use of strong, light and energy efficient materials, such as carbon nanotubes or graphene – particularly if they were planning to build extremely high, as the structures would need to bear their own weight and withstand hurricane force winds past a certain height.

© Skyscraper City

Futuristic Transportation for the World Population

You’d think getting around this enormous, congested city would prove troublesome, to say the least. If the pictures of Kowloon Walled City are anything to go by, there might not even be space for traditional, ground-level roads. Citizens would probably be reliant on a combination of public pathways, underground tube networks, monorail systems and airborne taxis.


The benefit of being so tightly packed is you wouldn’t have to travel too far to reach places. However, that means transportation networks must be efficient and punctual. Assuming the city will take many centuries to construct, technology will hopefully be innovative enough to make use of some really cool features.

Airborne taxis, which Uber are currently developing under the name Uber Elevate, would most likely be fully automated, taking up the slack of a hyper-busy public transit system and providing comfortable transport for wealthier citizens.

Given the relatively small size of the city, however, many people would probably just opt to walk to their workplace. Architectural Digest magazine predicts that transportation methods will be increasingly clean and efficient; bike and electric scooter shares will be on every corner, and green, low-carbon trucks will improve the last-mile delivery of consumer goods.

© Max Pixel

Strangely, this overpopulated megacity is starting to sound pretty good for the environment. Increased urbanisation favours pedestrians, and there would be fewer, if any cars on the road.

© Piqsels

We would, however, need to conduct manufacturing and processing on the edges of the city – which would cause a massive bubble-ring of smog to form. There would also need to be vehicles to transport food in from the surrounding agricultural zones – which are tended by robot farmers, by the way.

© Freepik/sompong_tom

Air pollution would quickly reach dangerous levels if we didn’t do something about it. Thankfully, the problem would all be concentrated in one place. So if we found a solution, we’d only have to implement it once. Large extractor fans could help isolate the breathable air. Or, we could use outward facing wind turbines to blow the polluted air away from the city centre, generating power at the same time.

© Flickr/U.S. Department of Agriculture and Flickr/Charles Cook

Sophisticated arcology would make use of widespread rooftop gardens and vertical farms in order to maintain oxygen levels and supplement food production. A large number of beehives and beekeepers are necessary to pollinate these plants and to ensure a steady supply of honey. Visiting these gardens would hopefully satisfy people’s desires to be around nature, which would be crucial if you lived in a sprawl of this magnitude.

Possible Economic and Social Issues

With the basic structure set out, lets talk about the Economy and any Social Problems that may arise. What sort of effect would living in a city like this have on people’s psychology? Would there be greater levels of intimacy, connection, and sharing? Or would we see social breakdown as people get sick of living on top of each other?

It would be a mixture of both, probably. In an article about large cluster cities in China, the Economist mentions the theory of agglomeration benefits, which holds that the bigger the city, the more productive it is.

The city’s large integrated labour market would make it easier for employers to find the right people for the right jobs, leading to an overall increase in personal satisfaction and fulfilment. Knowledge would also spread more easily, and the large, concentrated working population would maximise the world’s total productivity.

But surely this lack of space would lead to terrible working conditions? Well, not necessarily – assuming industries have worked their way towards full automation, we’re likely to get robots to do most of the tiresome work for us.

© Wikimedia Commons

Humans would still in charge of quality control, programming, robot mechanics etc. However, many people would not have to work at all – at least not in the traditional sense of employment.

That seems great, but it would all depend on the system of government the city settles on and who’s in power. Forming a stable version of democracy would be challenging with such diverse, densely packed communities. This dense environment will heavily influence crime and other social problems. Various studies, new and old, show that high-rise living can lead to crime, stress and delinquency. Kowloon Walled City had notoriously high rates of prostitution, gambling, and drug abuse. The local triads were on charge of these criminal activities, although the non-criminal community was apparently tight-knit.


Increased automation means fewer working hours and more idle people. These people might well descend into criminal activity if not taken care of properly. It would also be far more difficult to catch criminals in the massive maze of entangled streets. So we would probably enlist drone police squads to do this for us.

This is all starting to sound pretty Orwellian to me – a dystopia with the look and feel of Blade Runner. But did we really expect the all-inclusive megacity of Nueva Estonia to turn out any different?

Disease Outbreak Could be a Disaster

Probably the most serious issue would be disease outbreak. Such close quartered living would encourage fast spreading of new viruses, and there would undoubtedly be a massive vermin population to help with that.

© Peak PX

People’s immunities would vary drastically, given that they would be from different cultures and climates. We could expect some serious outbreaks early on in the foundation of the megacity. Medicine, by this point, would hopefully be effective enough to treat and prevent a truly disastrous epidemic. And automated medical robots would certainly help meet healthcare demands, and prevent patient-to-doctor infections.

© Defense.GOV

There are countless more issues the city would have to deal with, such as waste management, water and energy networks, and well as fire safety. But we’re inventive creatures, and I’m sure we’ll find some clever solutions rather quickly.

So what would happen to the rest of the planet if all the population of the world was crammed into Estonia? Good things, I imagine. Do you know what is the only conceivable scenario in which we’d have to live in a hypothetical megacity like this? Only if we continue polluting the world environment to such an extent that it becomes unliveable. Then, the only way to protect the population would be to create an Anthropocene bubble zone where everyone had to live.

© Art Station/Marc Scott

Which begs my final question: do you think this kind of world megacity is inevitable? And do you think it would look anything like the idea set out in this video? Maybe you have some big ideas for a future megacity? Let me know your thoughts in the comments down below.

You can watch this article in video form below: