Transcription
Cities are more than just buildings and streets. They are living, breathing entities shaped by human ambition and necessity. But as we stand on the precipice of the future, will our cities soar into the heavens, sink into the earth, or stretch across the [Music] stars? If you could design the perfect city, what would it be like? A sprawling garden paradise? A towering metropolis reaching into space, a floating city drifting among the clouds, or one hidden deep underground with its own artificial sun?
Today, we'll explore the cities of the future and the incredible ways they might reshape our lives. From skyscrapers stretching to the heavens to entire civilizations built among the stars, the cities of tomorrow won't just be bigger. They'll be smarter, greener, and more interconnected. Some may stretch across continents, while others might hover above the clouds or carve vast subterranean realms beneath the Earth's surface. Yet, alongside these breathtaking visions, there's always the shadow of dystopia—polluted, overcrowded, and lifeless concrete jungles. Which version will our future cities become?
To answer that, let's first look at how we got here. When I was born in 1980, the global population was around 4.4 billion. By 2000, it had grown to 6.1 billion. By 2020, it had reached nearly 7.8 billion. The world isn't just getting more populous; it's getting denser, taller, and more complex. The cities of the past grew outward. The cities of the future—they might be almost unrecognizable. For one, they might not be on Earth at all.
On Earth, though, rapid urbanization has reshaped how we live. More people means denser cities, longer commutes, and the challenge of balancing resources. Some worry this will lead to soulless mega-cities, but others believe it presents a unique opportunity to build something better. As the global population continues to rise and environmental challenges grow, cities must evolve to meet the needs of future generations. Conversely, if populations stabilize or decline, especially in urban areas, we could see vast stretches of empty, decaying architecture.
Urban centers today face significant challenges, including resource depletion, pollution, overpopulation, underpopulation, and aging populations. These issues demand innovative solutions to ensure sustainable and efficient living environments. Every city tells a story of triumph, of struggle, of adaptation. But in a world of AI-driven automation, harsh environments, and space colonization, what kind of stories will our future cities tell? We'll be discussing these as we go, but we'll also ask, what might these future cities look like? Will they rise into the skies as massive arches spread beneath the Earth's surface or even drift among the stars?
Advances in artificial intelligence, automation, remote work, online shopping, and renewable energy are already shaping the urban landscapes of tomorrow. This episode will explore the possibilities, opportunities, and risks of these emerging cityscapes. As we ask, how will technology and innovation redefine urban life in the future? There are many different possibilities for where we might want to build, both for aesthetic reasons and for practical ones. Would you rather live in a city where the sky is your backyard, where you walk among the clouds, or one so deep underground that the sun is a distant memory? The choice may not be as simple as it sounds. What would it be like to live in a tower so tall you look down on the clouds, or in an underground cavern so immense it had its own weather, deep under the sea, or one floating in the sky or hanging in orbit?
Today, we'll explore the places we might live and what life in them might be like. And if that sounds like fun, hit those like and subscribe buttons and grab a drink and a snack and let's dive in. I spent time in cities all over the world. And while I appreciate their architecture, I've always preferred wide-open spaces or forests. My wife and I live on a farm in rural Ohio, miles from the nearest store. But even out here, we still feel connected to major urban centers: Cleveland, Youngstown, and Erie, PA, each about an hour away.
This is why I tend to imagine the cities of the future as blending urban, suburban, and rural elements. Not everyone wants to live in a towering skyscraper. But that doesn't mean we can't create spaces where a variety of lifestyles thrive. This means I'm probably a bit biased when it comes to imagining the cities of the future. When I picture a grand space habitat, I tend to envision it with more suburban and rural elements rather than just towering skyscrapers and high-rises. Not that you can't have both. And I also think this perspective helps as cities once notorious for charging an arm and a leg for a closet-sized apartment have actually been growing larger in terms of average accommodations. Green parks and other third spaces have also been on the rise. While the classic image of smog-choked streets in a world where every tree has been cut down no longer seems likely, let alone the grim certainty many predicted when I was a kid. Ironically, those predictions often place that bleak future in the here and now.
We'll skip the inevitable humorous comparison of how close Los Angeles is to its fictional depictions in classics like Blade Runner, set in 2019 and my own personal favorite film. I was born in California and I've been out to LA a few times since 2019 and didn't think it looked much like its common cyberpunk portrayal. Though at the time I'm writing this, LA is literally on fire. And humor aside, fire has wrecked a lot of cities, and also many have risen even greater and more grand afterwards. And I don't doubt the city of angels will do the same.
We previously explored the near-term future and the services people will want over the next few decades in our episodes on smart cities. On the flip side, we examine the more classic sci-fi dystopian mega-city in our episode on mega-cities. While we will revisit some points from both today, I'd like to branch out more. And with trees in mind, let's begin by dipping into vertical cities and arcologies.
Now, verticality in cities is nothing new, but it's also dreadfully expensive. It is easy to forget that even a place like New York City, which has on the order of a million buildings, most are just a few stories high with only a few hundred skyscrapers. Scaling up a city isn't just about adding more buildings; adding more changes how we move around. Let's say your city doubles in size. You might think that means travel time just doubles. But in reality, it gets much worse. Most people don't live in the very center of a city, and most places they want to go aren't there either. If you pick two random spots in a city, the average distance between them is almost the radius of the city, or about 45% of the diameter, 128 times the radius divided by 45 pi to be exact, for a circle anyway, which most cities are not. It's actually worse for your typical city sprawling along some river or coast or both, but it still scales this up the same. Doubling a city's width potentially quadruples its population. It also doubles the average distance between points and thus commute times even before factory and traffic congestion, popular spots, or bottlenecks like bridges. And the result, unless transportation keeps pace, bigger cities means longer commutes and more congestion. This is where vertical cities come into play. Given a large enough population, you might indeed need multiple versions of these. But another solution to urban sprawl is to build vertically. A city that averages 16 stories in height would have a quarter of the commute times, or at least travel distances, compared to an equally populated city that's only one story tall. If congestion or public transport inefficiencies doubled commute times, you'd still be far ahead in terms of accessibility and efficiency over the wider and flatter town.
However, balancing vertical expansion against infrastructure costs is tricky. Taller buildings require more expensive materials and greater engineering complexity, while sprawling cities demand more roads and maintenance. Advances in construction materials and automation have made taller buildings more viable, and this trend will likely continue. But if you build high enough, you eventually hit the vertical problem where in total transportation becomes a major bottleneck. Imagine living on the 150th floor of a mega-structure. You step out of your apartment, press the elevator button, and wait… and wait… and wait some more. Minutes pass before the doors finally open, only to reveal a packed elevator. You sigh and wait again. In a city where streets are vertical, this is the equivalent of rush hour traffic, but instead of seeing gridlock, you're stuck in a steel box moving at 20 ft per second. This is the elevator conundrum. The taller the building, the more space is needed for vertical transportation. But here's the paradox: as skyscrapers grow taller, so does the number of people relying on elevators. As the elevators multiply, they get more and more of the building's interior. Without solutions, a building could reach a point where over half its floor space is dedicated solely to elevator shafts, making vertical expansion beyond this pointless.
So, how do we fix this? The answer lies in express elevators, decentralized vertical layouts, and sky bridges connecting multiple structures—dedicated express elevators to certain floors, faster elevator speeds, and shared-use facilities such as laundry rooms on every floor all help reduce elevator dependency. Technology also plays a role: smarter, faster elevators, remote work reducing commute demand, or flexible work schedules that stagger peak elevator usage. Ultimately, if a building grows tall enough, it must adopt the same strategy that cities use, creating smaller self-contained communities within the structure or even linking buildings together via sky bridges. This prevents people from needing to take the elevator all the way to the ground floor every time they leave their home or workplace. This is the essence of the modern concept for an arcology.
Originally, arcologies aimed to blend architecture with ecology, envisioning self-sustaining villages composed of many small homes. Over time, however, the idea evolved into super-tall, super-wide structures capable of housing entire communities complete with homes, stores, workplaces, and even on-site food production. In the United States, the average apartment size is approximately 916 square ft (85 square m), typically housing about 2.5 people. This equates to roughly 366 ft (34 m) per person. You obviously need more for hallways, places to work or shop or relax. And of course, elevator shafts—maybe more on the order of 1,000 square ft or 1,000 square m a person to keep things round. A building 100 m on each side (square) and say 100 floors tall (or a million square m) would be offering you residence, workspace, commercial space, and recreational areas for 10,000 people. That might seem small for a city in terms of the great metropolises, but that's bigger than most cities. In fact, of the roughly 20,000 incorporated places, cities, and villages in the United States, 84% of them have populations of 10,000 or less, and only 10 of those cities have a population over a million. The future isn't necessarily bigger cities, either. It might be many more smaller ones. That's not exactly an impossibly big and tall building, either. We have taller and wider ones already, but it gives us a notion of scale. And even if future folks wanted twice the living room and ditto those other spaces, we would be talking a population of 5,000 in such a building. And that's the minimum threshold to be a city, not a village in a lot of the US, including my home state of Ohio. It can have its own schools and shops. And when you factor in remote work and shopping and schooling, it would decrease your traffic down to the ground floor a lot.
If a skyscraper is a single tree and an arcology is the whole forest, these aren't just buildings; their entire ecosystems are designed for a future where space is at a premium and efficiency is king. Now, where this really scales up into arcology territory, it's not just about size. The square-cube law states that as an object's size increases, its surface area grows with the square of its length, while its value and mass grows with the cube. If you double a building's height and width, you get eight times the interior space, but only four times the window area, making much of that extra space less desirable for living. Even setting aside safety regulations, people like windows. So, you can't just build massive windowless monoliths for residences. However, you can if much of that space isn't meant for housing or for the parts of workspaces or third places that people actively use. A third place, incidentally, is a term for places folks spend a lot of time that isn't their home or workplace—the first and second places, respectively. Some places are none of the above or might be a workplace but not need windows. A windowless warehouse probably works just fine. And so does a huge interior garden park with artificial lighting, which is getting around the need for a window by simulating the outside and thus not only does not need windows, but provides you an interior area people might be okay having windows looking out on instead of being on the outside. This is very important to space habitats where the outside is actually the floor and where windows might be rather nauseating to watch since the places spin around fairly quickly.
But arcologies often take this concept even further, incorporating vertical farming into their design. This could mean filling the interiors of massive wide buildings with vast hydroponic farms, growing food within the structure itself. I'm a bit dubious about vertical farming ever becoming a viable primary food source for an entire civilization, but it can be useful for bulky, short shelf-life crops like lettuce and other greens. By growing them inside the tower and selling them on-site or nearby, you eliminate many of the costs associated with transporting fresh produce from outside. It doesn't even need to be economically ideal. Indoor food production and storage could serve as a strategic safeguard against embargos or seizures, ensuring food security in extreme scenarios. You might grow some crops while keeping large reservoirs of compact, calorie-dense foods, particularly fats and dehydrated goods. Meanwhile, the interior garden space could be used not just for food production, but also for air purification, scrubbing carbon dioxide and other particles from the atmosphere. Air and water recycling will be day-one necessities on space habitats and off-world colonies, but they might become essential for Earth's largest cities as well. A city dense enough can't always rely on weather to clear its air. Even if we eliminate all artificial pollutants, the atmosphere is still full of 100% natural irritants like pollen and dust—things we don't want to breathe in large quantities. If air must be filtered in high-density buildings anyway, integrating green spaces and hydroponic farms could be a practical solution, enabling even larger urban structures. Hydroponics and climate-controlled greenhouse conditions are vastly more productive than your normal open-air farm in terms of space, too. Needless to say, these interior spaces could also be repurposed for storage, transit hubs, or even vehicle garages. People like cars; telling them they should not tends to be ineffective. But high-density structures like these also make mass transit more viable, too, reducing overall transportation burdens or still accommodating personal vehicles. See our Hive Worlds episode for some of the more extreme versions of how big this can go and why you might even turn to farming up in space and bringing food and power down. But in the short term, this is likely the pathway to larger and more affordable mega-structures by designing buildings that handle more aspects of daily life internally while shifting many functions to digital alternatives. You're not commuting because you either work inside the building or work remotely. And even if only half the population does one or the other, it helps a lot with congestion.
What's interesting about this shift is that it could bring major societal changes. Historically, most people lived and worked in the same place for their entire lives. But today, people chase jobs across the country or even the world. You go off to school far from home to secure a job that requires relocating, and that company shuts down, transfers you, or you simply change careers, you move again. Remote work has its pros and cons. I mostly work from home myself and I quite enjoy it. The only real challenge is keeping my office quiet enough for writing and recording. My kids can be a bit noisy, and since I homeschool them, it sometimes requires some juggling. Fortunately, my time in the army taught me to write even in war zones or near loud motor pools. So, for the most part, I just need them to stay quiet while I'm recording. Accommodation was achievable. They look forward to moments like these when I'm recording because they get to zone out in front of the TV. That aside, remote work is not for everyone or every job. But between that and the rise of self-contained mega-structures, we might see a return to people living and working in the same neighborhood their whole lives, which by and large tends to be a good thing. Of course, you can still move around if you want, though a nomadic lifestyle can be fun, too. But there's something to be said for staying in one community long-term and truly getting to know the people around you. I won't soapbox, but I do suspect that our detachment from that way of life hasn't exactly been a net positive for modern society. Emphasis on the word net because it probably has had some benefits for us. And for many, there is a very real and understandable desire to lead the community you were in for personal reasons. And as always, our hope for the future is not to find the best path for everyone, but to enable a lot of different good paths for individuals to pick the one that best suits them or that they feel best suits them. The right to even make bad choices is kind of important. And many a city layout or plan has been the product of bad choices or even more often rather reasonable ones that got themselves delayed in debates and obsolete by some new technology or cultural interest. One downside of really big buildings is they are epic efforts to construct and major singular investments that can be ruinous to an entire local economy if they fall through. Repurposing giant old factories or malls or even old school buildings is rough. Not all cities have a ground floor either. Many have their undergrounds, for instance. Consider Toronto and Montreal in Canada, each of which have over 30 kilometers of interconnected pathways underground leading to restaurants, shopping, and entertainment.
Some future cities might stretch into the skies. Some might carve into the earth. Some may run out underwater on the coast along the seafloor, and others may drift on the waves or hover among the clouds in the future. But no matter where they rise, one question remains: will they be paradise or a prison? Needless to say, this logic applies even more to something like an arcology or a space scraper or subterranean cities or artificial islands floating on the sea or under or in the air or the islands in space—vast space habitats or settlements built on new planets, moons, asteroids, or comets. We have deep-dived all of these topics in their own individual episodes, but thought we might look at each briefly today and ask what life would be like there and what challenges might apply. How they might be a utopia or fall into dystopia that will be a challenge to the citizens of the future—a test of their wisdom and ambition. The sky used to be the limit for them; it's just the foundation for something even taller. [Music]
What powers the cities of tomorrow? Solar fusion or something even more powerful? In our latest Nebula exclusive episode, Antimatter Propulsion, we explore how antimatter could become the ultimate fuel capable of powering starships, entire planets, or even vast space-born cities. It's the kind of limitless energy that could reshape civilization itself, assuming it doesn't destroy us first. While today's episode dives into the design of future mega-cities, arcologies, and floating utopias, Antimatter Propulsion focuses on the technology that might someday power them. It's not just about interstellar travel; it's about fueling new infrastructures and ways of life both on Earth and beyond. You can watch Antimatter Propulsion now on Nebula, the creator-owned streaming platform where every SFIA episode airs early and ad-free alongside exclusive monthly content you won't find anywhere else. You also find brilliant videos from creators like Real Science, Simon Clark, and The Science Asylum. And don't miss The Sojourn, a Nebula original sci-fi audio drama that follows a distant human colony on the edge of survival with excellent voice acting and powerful storytelling. It's the perfect companion to our visions of tomorrow's cities. Sign up at go.nebula.tv/isaacur for a lifetime membership. Pay once and watch forever. For just $300, you can unlock hundreds of hours of smart creator-led content without worrying about subscriptions again. And that includes dozens of SFIA's monthly exclusive episodes as well as extended editions. Prefer to dip your toe in? You can also subscribe annually for just $36 a year. That's 40% off. And now back to tomorrow's skylines.
Space scrapers and space towers. Of all the futuristic city concepts, space scrapers—towers so tall they extend into the upper atmosphere or even space—might be the most visually striking. These mega-structures could serve as launch platforms, scientific hubs, or even self-contained cities, offering a unique way to reach orbit without traditional rocketry. The higher you go, the less atmospheric resistance, meaning launching cargo from such a structure would be far cheaper than from the ground. If built high enough, a space scraper could even serve as a stepping stone to an orbital elevator, letting people and materials travel to space with minimal energy costs. Life in a space tower could be spectacular. Imagine penthouses with views so high you could see the curvature of the Earth, or entire levels dedicated to floating gardens, scientific observatories, or luxurious entertainment hubs above the clouds. At extreme altitudes, the air would be thinner, skies darker, and the sense of isolation profound. A well-designed tower could offer a clean, controlled environment, shielded from ground-level pollution and overpopulation, with easy access to near-orbital travel. But it could just as easily become a nightmarish dystopia. The sheer cost and maintenance would be enormous, requiring constant stabilization against wind forces, earthquakes, and shifting ground foundations. Indeed, those foundations might need to reach nearly to the planetary mantle. Emergency evacuations would be a logistical nightmare. Getting down from a 50 km tall tower in a crisis is a problem no modern fire department can handle. If strict corporate or governmental control ran the tower, it could become a self-contained authoritarian micro-state where access to lower levels or escape was tightly regulated. The 2012 movie *Dread* takes place in a smaller version of one of these and highlights the problem spectacularly. And then there's the psychological effect. Life in a space scraper might feel like being trapped in a high-tech ivory tower, disconnected from nature and the rest of humanity, with only artificial parks and digital windows providing the illusion of a world below. Still, if the engineering challenges could be overcome, space towers might serve as the first stepping stone toward true space colonization, offering humanity a permanent, functional link between Earth and the cosmos. See our Space Towers episode for more discussion of their scale, uses, and engineering.
Subterranean cities. For as long as humans have sought shelter, the Earth itself has provided protection. Today, we still build underground—not just basements and tunnels, but vast subways, commercial districts, and even entire bunker complexes. Could the future see entire cities beneath the surface? The advantages are clear. Underground structures are naturally insulated, reducing energy costs for heating and cooling. They are shielded from extreme weather, radiation, and even many natural disasters. They are fortified against hostile action. They have potential on Earth as cities of their own or extensions of greater cities above, but underground may be the best option on many other worlds. A subterranean metropolis could provide unmatched security during global crises, whether from environmental issues, asteroid impacts, or nuclear war. In places where land is scarce, digging downward could allow for vast urban expansion without disrupting natural landscapes above. But life in an underground city might feel oppressive, dark, or isolated. Natural light would be limited, and artificial lighting, no matter how advanced, might never fully replace the psychological effects of sunlight. Air circulation and water management would require constant technological oversight. In extreme cases, a poorly maintained subterranean city could devolve into a stagnant, enclosed society riddled with infrastructural failures, poor air quality, and economic disparity between those living deeper versus those closer to the surface. If done right, however, subterranean cities could be vibrant, modern habitats. Expansive underground parks, mushroom forests, and crystal mazes, hydroponic gardens, and carefully designed lighting could create a comfortable, green environment, eliminating the dreary images of cramped dystopian bunkers. And while Earth may have little need for entire cities beneath its surface, learning to live underground could be a vital stepping stone for colonizing other worlds, where digging into rock or ice for protection against radiation and harsh conditions may be essential for survival. See our subterranean cities episode for more discussion.
Artificial island cities. Humans have long shaped coastlines to our needs. But artificial island cities take this to the next level—extending land into the ocean, creating floating cities, or even building massive anchored platforms. Floating or modular designs could allow sections of the city to detach and relocate based on climate, politics, or economic shifts. Life in an artificial island city could be idyllic: ocean views, clean energy from solar, wind, and wave power, and access to fresh seafood. The city may migrate, floating around over the course of a year. Vast ocean farms made from floating rafts of some material, which gives roots and nutrients something to cling to, might feed your city while beautifying the empty sea and…
Enhancing the local marine ecosystem with a supply of additional biomass and marine snow. However, maintaining infrastructure at sea is expensive, and storms and tsunamis pose risks. Corrosion, logistics, and freshwater supply are ongoing challenges. A floating city might feel liberating, but isolation and governance issues could lead to lawlessness or economic instability. Indeed, placing them in international waters to get around laws tends to be a major motivation for building them at present, and that could have some undesired consequences.
If well planned, these cities could expand living space for growing populations. But they could also become playgrounds for the ultra-rich, leaving the rest of humanity behind, or havens to pirates and criminals and illegal research. See our recent episode on marine habitats or our episode on artificial islands and seasteading. For more on building your own island and kingdom, underwater cities.
For centuries, humanity has dreamed of colonizing the ocean depths. Inspired by stories of Atlantis and futuristic visions of dome-covered seafloors, advances in materials and technology now make underwater cities a possibility. These habitats could offer a sanctuary for many problems, function as deep-sea resource stations, or serve as hubs for ocean mining and aquaculture. Being underwater provides built-in protection from hurricanes and surface radiation. And the deep sea is thermally stable, reducing energy costs for temperature control.
Living in an underwater city could be both surreal and isolating. Imagine walking up to a panoramic view of bioluminescent fish swimming past your window with artificial sunlight filtering through a dome. Daily life might involve farming algae, managing air and water recycling systems, or even exploring the ocean in personal submersibles. However, psychological stress from confined spaces, the need for constant maintenance, and the risks like structural failure or oxygen supply issues could turn this paradise into a high-tech prison. Indeed, we discussed using their lower levels for that purpose, an undersea Alcatraz. Without proper planning, underwater cities could become neglected, crumbling relics, or even eerie abandoned ghost towns. See our episodes colonizing the oceans and habitable wards ocean planets for more discussion.
Cities in the sky. Cloud cities suspended high above Earth or even higher in the skies of Venus could provide humanity with a new frontier of habitation. Whether using massive balloons, advanced aerostats, or rigid floating platforms, these airborne metropolises could exist where the air is cool and the skies are clear, offering a refuge from pollution, crowded lands, or even surface conflicts. Like raft cities, they could migrate. Some designs could hover above existing cities, acting as high-altitude suburbs, while others might drift freely on the global air currents, moving to stay in ideal climates.
A floating city could be breathtaking. Imagine walking through streets lined with gardens, looking down at the Earth from thousands of feet above. Energy could come from solar panels exposed to near-constant sunlight. No clouds blocking them for those high enough, while water might be collected from passing clouds above or below. However, gravity is an ever-present concern. Keeping a city afloat requires enormous amounts of lift, and any failure in the stability system could spell disaster. Daily life might involve restrictions on movements, reliance on advanced automation, weight limitations on personal possessions, and little room for error in resource management. Without a strong infrastructure, cloud cities could become fragile, expensive luxuries for the elite, or worse, traps doomed to plummet from the sky. See our episode Cloud Cities and colonizing Venus for more discussion of living the high life.
Space Habitats. We spent our entire existence tethered to one world. But from the moment we built our first true space habitat, humanity will have taken its first step toward becoming a multi-world species. For all of human history, we've lived within the constraints of Earth's surface. But space habitats offer the potential to leave the planet entirely and build new homes among the stars. Whether a vast O'Neal cylinder, a skinny Stanford Taurus, a compact Bernal sphere, a sprawling asteroid-based mining settlement, or any of the other space habitat designs we discussed in so many episodes, these artificial worlds could house millions in self-sustaining environments free from planetary limitations.
Unlike traditional planets, these habitats could be custom-built to suit any preference. Earthlike climates, exotic low-gravity environments, or even multi-tiered mega-structures with enormous land area packed inside a relatively small volume. Life inside a space habitat could be extraordinary. Imagine living in a city where the sky is curved above you, where agriculture is managed in towering rotating farms, and where gravity is precisely calibrated for comfort. Power would come from massive solar arrays or huge high-tech reactors. And air and water would be imported from cometary bodies or endlessly recycled. There would be no ruinous storms, no natural disasters, just perfectly engineered environments designed for long-term sustainability.
Space habitats could provide unparalleled freedoms, from microgravity recreation to the ability to create new societies unbound by Earth's borders and traditions. Yet the challenges are immense. Space is inherently hostile. Every breath must be manufactured, every drop of water conserved, and it is empty of everything but murderous radiation and dangerously fast micrometeors. The risk of failure is ever-present. A single breach could mean death for thousands. These habitats require enormous initial investments and ongoing maintenance to remain viable. Without strong governance, they could become dystopian enclaves controlled by corporate overlords, ideologues, or classic aristocrats in some new version of space feudalism, or isolated, fragile bubbles cut off from broader civilization. Some might devolve into sterile utilitarian machines more akin to giant factories than thriving cities. Still, if humanity is to expand beyond Earth, space habitats offer one of the most practical and flexible solutions. Unlike planets, they can be placed anywhere, orbiting Earth, stationed at Lagrange points, floating in deep space, or nestled safely inside very low-gravity moons and asteroids. They could be built in a matter of decades rather than the millennia it might take to terraform a planet. A successful space habitat could be a paradise of abundance and freedom, but a poorly designed one could be a lifeless husk abandoned to the void.
Cities on other worlds. Building a city is hard enough. Now imagine building one on an alien world where every breath must also be manufactured. Every structure must withstand the unknown, and every mistake could be your last. For centuries, humanity has dreamed of setting foot on other planets, building new homes under alien skies. Whether it's Mars, the moon, or the icy moons of the outer solar system, planetary settlements offer the appeal of an actual surface beneath our feet, an enduring sense of place in a vast and inhospitable universe. Unlike space habitats, planetary settlements anchor themselves in real terrain with all the benefits and limitations that come with it. They may also be more likely to grow into cities faster, as unlike on Earth, there's not much motivation to spread out to find fertile new lands to farm on. These planets are likely to be barren places where you must manufacture your own soil and where direct connection to existing infrastructure is likely to be vital.
Life on another world could be thrilling. Waking up to see a new sun rising over an alien horizon, maybe more than one or even a black hole. Walking in lower or higher gravity that makes you stronger. Or stepping outside in a sealed suit to explore a landscape untouched by life. A well-designed settlement would offer independence, with dome cities growing their own food, mining the local resources, perhaps even transforming barren worlds into thriving environments. Mars, with its potential for terraforming, might one day have blue skies and running water, while the moon could serve as a hub for interplanetary industry, its low gravity making it the perfect launch pad for further exploration. See our episodes on the domes of Mars and the gardens of the moon for some of the options for mid-settlement after the early days but before extreme terraforming.
Yet planetary settlement is a slow and difficult process. Unlike a space habitat which can be engineered to exact specifications, planetary environments must be adapted to, not designed from scratch. Gravity, atmosphere, and surface conditions impose strict limitations. The moon is airless, bombarded by radiation and covered in razor-sharp dust. Mars has a thin atmosphere and extreme cold, making every aspect of survival—air, water, food, and heat—a logistical challenge. Settlements must be buried underground or shielded by domes to avoid deadly cosmic radiation. And maintaining a stable supply chain from Earth will be critical for decades, if not centuries. Then there's the psychological challenge. A planetary colony may be vast, but it remains an isolated, enclosed environment where stepping outside without protection means certain death. They will be even more isolated on strange new worlds orbiting alien suns where the original landing site may grow into the first true city of that world. Over generations, settlers may become adapted to their world in ways that make returning to Earth impossible. Bodies shaped by low gravity, minds accustomed to seeing the stars without an atmosphere to obscure them. If a colony fails, it won't be abandoned like a failing city on Earth; its residents will have nowhere to go. Still, for those willing to take the risk, planetary settlements represent the next great frontier. They could become the birthplaces of new cultures independent from Earth, shaping their own destinies. Whether a utopian new beginning or a desperate struggle for survival, these off-world outposts will define the next chapter of human civilization. In the end, this is perhaps the most important thing to remember about cities of the future: most of them will not be on Earth, but far away in space and time. [Music]