In a futuristic sci-fi world (galaxy?) I'm building, warfare has become highly regulated and commercialized. When two corporations meet on a deserted planet to do battle, they're followed by all sorts of ships: from weapons dealers to mercenaries, everyone wants a slice of the action.

But the biggest and perhaps craziest of them all is the fleet of colonists. Protected by the laws of pseudo-omnipotent post-mortals and driven by the promise of hungry soldiers with full wallets and mountains of scrap metal, these colonists descend upon the battlefield like vultures, building up a city of restaurants, hospitals, brothels, and refineries in a matter of days.

This raises my question, what's the fastest way to put up a city like this? Assume the colonists are about a million strong, and have all the materials they need safely in orbit at the start. They need to get these materials down to the planet, assemble them, and have them in working condition as quickly as possible.

Assume near-futuristic technology, so no transporters, replicators, or magical portals to the alternate dimension of Amish housebuilders. However, energy is effectively infinite and incredibly cheap due to fusion reactors.

Also assume the planet in question is Earthlike- soil, water, minerals in places you'd expect them to be, and a wide variety of terrain formations.

I want this city to outlive the war, and eventually become a permanent settlement. The idea is to use the war to gain some initial capital while the sustaining infrastructure is developed, so I don't want all the buildings to blow away in the wind once the soldiers leave.

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    $\begingroup$ My first thought: just land your city/spaceship right on the ground. (Although the SG-verse does have replicators (in a sense), transporters, and magical portals, they didn't use any of them to move Atlantis.) $\endgroup$ Apr 9, 2015 at 18:07
  • $\begingroup$ You can take a look at post-Communist Eastern European countries, where such projects were performed in the 1970's and 1980's. A forced industrialization led to large masses of people being displaced from villages (sometimes "persuaded" by demolishing said villages) and settled into towns. A large number of pre-fabricated flats were built in a very short time, so that even today you can see towns where most of the population lives in one of the 3 or 4 exactly similar apartment layouts. $\endgroup$
    – vsz
    Apr 10, 2015 at 6:21
  • $\begingroup$ FTL is not near-futuristic. $\endgroup$
    – Taemyr
    Apr 10, 2015 at 9:40
  • $\begingroup$ They have FTL travel but nothing else is advanced beyond us? I think the underlying tech would be enabling in more ways. $\endgroup$
    – JDługosz
    Jun 17, 2016 at 19:18
  • $\begingroup$ @JDługosz well, in this case the underlying tech isn't all that sophisticated. It just required more space, energy, and lack of gravity than we've had access to. I'm using the FTL technology to power my artificial gravity too, so I'm sure there are other applications, but the technology is still in its early stages, and still pretty dangerous to mess around with. $\endgroup$ Jun 17, 2016 at 20:01

9 Answers 9


1 - Modular Ship/City

I'd say a Modular flotilla/ship would be the fastest way (If you indeed have infinite energy supply)

Some modules are immediately set in orbit for planetary communication services, weather, etc...

The Main module also remains in orbit as a general space station/dock

All other modules are sent in succession down onto the location of choice, once landed they are easily stripped of their engines that are stored if needs be (or left if they prefer waiting to see if their venture is profitable).

On a successful colonization project the engines can be sent back up with a single module for re-use elsewhere, or modules are repacked and take off from a launch site to reattach to the Main module and move on to the next planetary conflict.

Each module basically has it's "base" (engine) and can easily be detached from it. I see them as large containers that can serve either as restaurant/entertainment/living modules in space or on the ground, making up effectively their spaceship or their city.

2 - The underground city

I guess Digging might work, just launch supply crates and a couple of drilling/torpedo robots and you could have a network of caves ready to accommodate large numbers of peoples. I guess this would be useful for harsher climates. This would have a bonus of protecting the city from any global scale collateral from the war. (Even though wars are regulated, there is always a risk)

You would also have the option of setting up a network of cities to reach the different army bases more efficiently, rather than concentrating on a single hub. It may also present a number of interesting perks for once the war is over, and is a lot more cost effective in that you can move on to another conflict without having to rebuild all your modules for the next planet. (If you choose to leave the colony on the planet)

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    $\begingroup$ You beat me to it! $\endgroup$ Apr 9, 2015 at 16:13
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    $\begingroup$ I think everyone thought of Modules right away. And unless someone dreams up scientifically viable Dragonball-like magic capsules, I can't really think of any other way to "instantly" create a city. I guess Digging might work, just launch supply crates and a couple of drilling/torpedo robots and you could have a network of caves ready to accommodate large numbers of peoples. I guess this would be useful for harsher climates $\endgroup$ Apr 9, 2015 at 17:00
  • $\begingroup$ the module city has no streets. Which is another way of saying everything will be covered in mud after the first rainfall. One million people can churn up a truly stupendous amount of mud whilst walking around. $\endgroup$
    – Racheet
    Apr 10, 2015 at 9:58
  • $\begingroup$ @Racheet Good point. The building modules would have to include the traffic system. So you'd have bunch of modular building surrounded by their own "roads" and then connect them with modular viaducts? Maybe some "major road" modules to provide straight roads? This would connect the building modules for other infrastructure and leave some empty land between modules for parks and gardens. $\endgroup$ Apr 10, 2015 at 10:13
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    $\begingroup$ For the modular city I'd have an easier time imagining some modules being foraging modules and quickly building gravel roads (and eventually concrete or some other type of roads) than having whole modules only for roads. $\endgroup$ Apr 10, 2015 at 14:12

This would be most easily achieved by pre-fabricating buildings and then installing the key equipment in the fabricated structures. Currently, you can blitz-build a pre-fab in a matter of weeks, and with larger 3D printers (mounted into ships, or utilising/mulching the local rock in giant PrinTrucks) you could conceivably reduce this even further. A million colonists, unbound by local planning law and specialised in this process, could set up a city in a matter of weeks. If they have the good sense to pre-fab some generic modular components before they even hit land, they might be able to speed this up even further by fine-tuning the modular components based on the planet while they're still in orbit, and using native resources for specialised buildings only.

Scaling up to include the colonists, soldiers and hangers on (two armies, assuming the entire resources of NATO on each side seems reasonable for a planetary battle) gives us a total of 8.2 million people inhabiting two cities, or 4.1 per side. This means each side has to build a city the size of Alexandria before they have enough space for everyone. It's a tall order.

  • $\begingroup$ The colonists wouldn't have to build housing for all the soldiers in each army. They'd have their own facilities, probably built in the same way. Though I guess overnight accommodation would be appreciated. $\endgroup$ Apr 9, 2015 at 16:33
  • $\begingroup$ Ah, I took from your question the idea that the civvies would be housing all the hangers on, and why would you barrack the soldiers so far away from all these shops, brothels and whatnot? Gaining capital is also easier if you can get grants from the commercial war partners. $\endgroup$
    – Rowanas
    Apr 9, 2015 at 18:16
  • $\begingroup$ Good point, I never thought of it that way. $\endgroup$ Apr 9, 2015 at 18:24
  • $\begingroup$ why barrack the soldiers far away from the good stuff - precisely so they won't be unfit for battle when called on. All those brothels, all that awkward itching... all those bars, all those unpleasant headaches... the military would want tight control over what their troops do for good reason. $\endgroup$
    – gbjbaanb
    Apr 10, 2015 at 15:32
  • $\begingroup$ @gbjbaanb Also a solid point, however he did say that it was highly commercialised. The corporations in charge of the goods being sold would definitely want soldiers buying, especially if they could work out sponsorship deals with whoever's signed the army. $\endgroup$
    – Rowanas
    Apr 10, 2015 at 17:59

What about inflatable (thick wall) tents, with locally sourced rocks as ballast, to stop them from rolling away? Once inflated, the tent becomes completely rigid, at least while the air is still in the walls.

You could even land them just by dropping them from orbit and inflating the tent just before impact, a la Mars Pathfinder.

Use solar energy to run pumps to evacuate the tents when you leave, retaining the air in pressurised tanks so there is no need to renew it between drops.

Not every building could work like this, but shops and restaurants surely could, given a tough enough air-bag material.

  • $\begingroup$ Or a variation of this would be a structure that inflates and then become rigid. This puts the buildings in place but not their contents. It would be great for living & warehousing spaces but not for factories, vehicles, and other necessary equipment. $\endgroup$
    – Jim2B
    Apr 9, 2015 at 19:25
  • $\begingroup$ @Jim2B That is more or less what I meant! $\endgroup$ Apr 10, 2015 at 2:24
  • $\begingroup$ Julian May's Pliocene Exile series has a technology much like this, called decamole. Depending on the size of the object and the required mass, they ballast them with water or sand. One character even has a decamole sailing yacht - he can't take it with him into Exile because there's no ready source for the liquid used in the keel (mercury, if my memory serves). He still has to add complex mechanical parts like the engine, but the boat itself folds up into something that fits in luggage. $\endgroup$
    – T.J.L.
    Apr 10, 2015 at 12:58

Don't forget that Freeman Dyson did some calculations as far back as the late 1950's-early 1960's as to the ultimate size of an ORION nuclear pulse drive ship.

Using 1950 era technology, he postulated an 8,000,000 ton starship with a drive plate diameter of 400m. This would be essentially a huge city in space. Today, we could probably do much better. The ship would need some sort of FTL to get to the "arena" planet, and we should postulate some sort of pure fusion device for the pulse units, so there is little or no radioactive fallout. More modern iterations could use lasers or ion beams to ignite very small fusion fuel capsules at a very high repetition rate in order to have the same effect.

The fantastic performance of the ORION pulse drive (the only high thrust, high ISP drive known using current physics) allows you to theoretically take off and land on a planet in one shot. Once on the ground, you could extend parts of the ship to create more room for your business district, and retract everything once it is time to take off again.

This way everything is self contained, and the commercial travellers will not have to take much time at all to get set up for business.

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    $\begingroup$ I have some issues with using ORION to land in a place I intend to live. $\endgroup$
    – Taemyr
    Apr 10, 2015 at 9:45

They could land their modular ships and link up outside of the battlefield. I am thinking that each ship is a modular part of the city. You land the mother ship (town hall) in the central part of where you want your city to be.

You then land the other modules in a cascading ring around the town hall. This allows you to set up shop relatively quickly and you can get to selling your goods (contained in a separate module) to the weary soldiers.

You would want to position your city on a hill (to stop the soldiers from being able to easily take your goods from you, which is what I would do if I were them. You would want plains around your town to make room for future farming (because you cannot rely on other colonies for re-supply when you run out of supplies).

Since the goal is to sell food to hungry, well-paid soldiers you would have to have a decent security force to enforce your prices. You would want the plains around your town to be surrounded by lightly forested terrain to create easy housing in the future expansion of your settlement.

I would like to point out that you would want at least two smaller settlements. You would want one to care for each side of the war. One serves army A food and medical supplies while another serves army B.

  • $\begingroup$ In my setting, I'm not really worried about the soldiers looting the city, or even both armies being in the city at once. Like I said, the war is regulated by some pretty powerful people, and the city is effectively a neutral zone. However, your considerations are certainly constructive. $\endgroup$ Apr 9, 2015 at 16:29
  • $\begingroup$ @DaaaahWhoosh I would like to point out that if the soldiers are in lack of supplies it really doesn't matter what their superiors say. If I were a hungry battle-weary soldier and I had to choose between following the orders of my annoying and wealthy CO and feeding myself :) $\endgroup$ Apr 9, 2015 at 16:34
  • $\begingroup$ Oh, it's not the superiors who're saying it. It's the ultra-powerful Galactic Admins that have been preventing galactic annihilation for millenia by literally pounding dissidents into dust with enormous hammers. But I see your point. $\endgroup$ Apr 9, 2015 at 16:38
  • $\begingroup$ Certain components of the ship (ahem, the drive system) would be too valuable to waste this way. But you could certainly do this with the cargo, empty fuel tankage, and habitat sections. $\endgroup$
    – Jim2B
    Apr 9, 2015 at 16:41

Some other variations of the answers already provided are:

Prepositioned equipment.
Landing the necessary equipment before the arrival of the inhabitants.

von Neumann machines
Classic von Neumann machines just self-replicate. Instead this would self-replicate and then begin preconstructing the city prior to the arrival of the inhabitants.

This mechanism allows the machines to be preprogrammed with set objects. For example:

  1. Start with space port construction
  2. Then replicate until $ x $ number of machines are created
  3. Then locate necessary mineral resources
  4. Then site mineral extraction equipment and facilities
  5. Then site mineral refining equipment and facilities
  6. etc.

In a story you can have the machines be at any state you desire by the time of the arrival of the colonists.


Mobile City

Why construct a new one each time? Just build the entire city to be movable, with cheap energy you can lift the entire thing to orbit and take it to the next planet. Then land and start over.

Edit: While it would be tricky to build a totally rigid structure of that size, since we have cheap energy we can use tons of small engines instead of a few big ones, and allow the structure to flex (not extremely, but a bit). The engines can be networked together and controlled from one single point so it doesn't pull itself apart.

It won't be incredibly maneuverable, but as it's a neutral target it technically shouldn't need to be.

  • $\begingroup$ Even if the energy's cheap, I'd still think the necessary technology would be absolutely massive, and thus incredibly cumbersome to maneuver. Unless you'd care to expand your answer and prove me wrong. $\endgroup$ Apr 9, 2015 at 20:01

Houses can be built very quickly, I think there is a world record of a little less than 3 hours. A group of well trained and well organized families can have their homes up and running in a day.

The next day stores, saloons and houses of ill repute are up and running.

The only problem is foundation. These buildings need some thing solid and level to stand on.

Some technique to place steel pillars into the soil in minutes would be required. Even in area where the soil is a bit swampy, a foundation built this way can be 'almost' permanent. Castles, like this one, supported by oak pillars are still standing after several hundred years.

Then put up the sidewalks like in the old west.

A large town will just need materials ferried down from the spaceships, a large number of machines to hammer steel pillars into the ground, and if they had a small crane on them, it might help, and just lots of people. The town will be up and running in a few days.


Build the city building by building, block by block in orbit, then drop the pieces down and with minimal surface preparation you should have a bustling city in no time - because the city was built while they were traveling to the new planet.

Once the city is built, send up raw material and start building the modular pieces for the next city.

The city itself might be rather expansive and large, but packed flat you'll find most of it is empty space enclosed by walls with built in ducts/energy/etc.

Further, it's modular enough that the actual building designs can be altered for specific needs. Planet has an unusually high gravity? Shorter, wider buildings can be made out of the same modular pieces. Planet's atmosphere isn't perfect? Sidewalks and roads can be covered and sealed with only a little building space lost due to panels being used for that.

Once the ship has taken on enough materials to build another city and has built up most of its stock of modular panels, it moves on to the next planet.

At the next planet it's already build many of the smaller and most important structures, and can plop them down while it assembles the others before plopping them down.

I expect the entire city can be build in a matter of weeks, with the initial services and skeleton taking only a few days.


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