I've worked a couple of Habitat for Humanity mass builds where entire houses go from a poured foundation to complete in the course of a few days, and whole neighborhoods are built in a week. There's a video made a few years back where they finished a whole house in a day, including pouring and setting the foundation, using some magic cement from the US Corps of Engineers. Then this week, someone asked this question on WorldBuilding SE and one of the answers mentioned "Sunomata Castle", a fortress in Japan that was, according to legend, built overnight.

In China, in 2015, a construction company built a 57-story skyscraper in 19 days. Here's the 1.5 minute time-lapse video.

Those are real-world examples. Fiction is full of buildings raised from nothing, whether by machines in anime or Superman's Fortress of Solitude raised by kryptonite crystal. And so, I would like to know...

What is the largest building that we could build in the modern world overnight? I'm looking for tallest first, with largest footprint as the tiebreaker. I'm pretty sure we can clear-cut and put up walls for a pretty huge area very fast, but the height is the interesting challenge because of the foundation issues.

You're free to use any pre-built materials you want in your answers, but the ground you're building on is a virgin empty plain, like west Texas. No support services, no prepared ground, but also no trees to have to worry about clearing out. No roads or shipping lanes, but assume your staging area is just over the horizon (about 20 miles away). This building is supposed to spring up out of no where.

You have from sunset to sunrise on the [longest night of the year] nope: make that 12 hours. Bonus points if you leave enough time before sunrise to clean up all the construction equipment and clear the area, but that's not required. Just the building. EDIT: Damn worldbuilder technicalities of polar night. :-) You have 12 hours.

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    $\begingroup$ From sunset to sunrise on the longest night of the year... hmm, I think I will be building in a place like Svalbard during the winter :) $\endgroup$
    – Alexander
    Feb 17, 2017 at 19:56
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    $\begingroup$ What constitutes a building? Most high rise buildings are preceded by construction of a crane and scaffolding before the permanent building that is as high or higher. Must it be finished on the inside? As a rule of thumb a building is 50% of the way towards being finished and ready to have a C.O. issued when the exterior is done. And, what about water, sewer, utility service? Must it be off the grid? How near are any water treatment plants, natural gas pipelines, and/or electric power plants? Is there any available source of water at all? I assume no permits or zoning approvals are necessary. $\endgroup$
    – ohwilleke
    Feb 17, 2017 at 20:12
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    $\begingroup$ hey that was my answer XD But no the Sunomata Castle was constructed with the bare minimum. Mostly an outer made out of wood and a way for them to defend the walls. More like an outpost than a full on castle. It's been a while since I looked into it but it wasn't a full out castle like you would imagine in Europe. $\endgroup$
    – ggiaquin16
    Feb 17, 2017 at 21:02
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    $\begingroup$ If you are building in west texas, you better hope there are no Mesquite trees on your build site. Those things take a whole night to grub up out of the ground and tehy are very hard to kill $\endgroup$
    – Paul TIKI
    Feb 17, 2017 at 21:06
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    $\begingroup$ @PaulTIKI don't forget the thorns too....We have them in AZ too and a few times I have cut a branch that fallen on my head or scraped the body... those damn things hurt. $\endgroup$
    – ggiaquin16
    Feb 17, 2017 at 21:07

8 Answers 8


Easy: build a radio-tower type structure. These are essentially lightweight prefab structures that you tack together and keep straight vertically by guywires. Short radio towers are normally built in a few days, and towers in general are some of the tallest buildings in the world.

The bottleneck is pouring the foundation, but as other answers have noted, quick-setting concrete or shallow, wide foundations are tractable workarounds. It's also worth noting that the tower assembly can be completed partially (or if it's short enough, completely) in parallel with the foundation--and if you build on a rocky outcropping, you might be able to forgo a concrete foundation entirely.

Very rough estimate: I'd be very surprised if a 50 m (17 storey) tower couldn't be constructed in 12 hrs, and I'd expect with exceptional planning and some engineering, a 200 m (67 storey) tower could possibly be constructed in 12hrs.

  • $\begingroup$ Can you have multiple floors in such a structure? $\endgroup$
    – SRM
    Feb 18, 2017 at 23:50
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    $\begingroup$ @SRM Sure, but like everything about them, each "floor" will be rudimentary--more like a panel you walk around on with a hole in the middle for the elevator. $\endgroup$
    – geometrian
    Feb 19, 2017 at 1:01
  • $\begingroup$ After reviewing the links and taking into account the difficulties highlighted by the other answers, I've decided this construction method offers the best approach to maxing out building size for an "it appeared out of nowhere" building experience. $\endgroup$
    – SRM
    Feb 19, 2017 at 14:55

I'm going to assume a shell of a building with no frills on the inside. I'm also going to assume a bit of pre-engineering of the basic structure. Im' no architect, so you'll get the layman's ideas here. You get exterior walls, basic floors, and stairs to go from level to level. I'm thinking you might be able to get something 4 stories tall. Assuming unlimited manpower and equipment. your footprint can be about as big as you want.

I'm capping out the structure at 4 stories for the following reason: You need a foundation that will set very fast and with something that will run the entire height of the building. There is a 2 part epoxy called pole-crete used by utility companies to erect power poles. These poles are driven 6 feet into the ground and the surrounding hole is filled with the expanding foam epoxy. It expands and set in about an hour enough for a lineman to get up to the top and start running line (rough estimate). Anything you do is going to put lateral stress on each of these poles. The higher you go, the greater the stress on your foundation footings until the entire structure is up and bound together.

Again, I'm no architect, but I have a feeling that your one night condition means that this becomes the limiting factor to consider. You don't have time to build a more solid foundation. You might be able to stretch things a bit with sections of structure steel that only add height as each floor is completed and cross supporting structures are in place, but I don't think you can realistically get much more than that and have your structure last past the first thunderstorm.

If you want exotic, you could get a pretty substantial geodesic dome up very fast. That would get you a big circular building without the need of interior support columns. I can imagine a 60' high, 120'diameter shell going up on a west texas night. You even get a little bonus because your foundations don't get as much stress.

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    $\begingroup$ "erect power poles." [clears throat and blushes]. Good answer, just a shame I can't give you a second +1 for that part. $\endgroup$
    – Mrkvička
    Feb 17, 2017 at 21:36
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    $\begingroup$ OMG did not notice that! $\endgroup$
    – Paul TIKI
    Feb 17, 2017 at 21:53

This would really be a matter of transport. We can do away with all of the nasty 'setting of concrete' business by just going pyramid-shaped. And given pretty much unlimited preparations just over the horizon, why not just build the entire thing there and move it? Some pretty big buildings have been moved before, and I don't really see a reason you can't just stuff more wheels under a building other than having to move the wheels out from under again. But, if you just put in struts where the wheels were, that shouldn't be too big of an issue either.

Now the biggest factor limiting the height is the weight of the structure. You can get some pretty impressive scaffolding structures that wouldn't weigh too much, and if wooden (or other very light) panels qualify as floors and walls, I guess you can easily get a 10+ storey building rolled over in 12 hours, given some custom all-terrain transport.

It should also be possible to airlift in some fairly impressive structures, The helicopter with the most lift power can lift about 20 tonnes. If you've got some super light-weight materials, this should be quite a few floors (somehow there's not that much info on 'weight per floor' for buildings). Now you'll need to assemble these parts into a building, and judging from construction videos, it looks like it takes roughly an hour for a large crew and a crane to properly stack two prefab building parts on top of each other. Still sticking with the pyramid shape to avoid pouring any concrete that has to settle.

So, given 12 hours, enough helicopters to airlift all the parts, and a bunch of cranes, you can stack up to 10 or so 20 ton prefab parts into a building. So your max height will be 10 times the height of the 20 ton prefab pieces.

With a few more days you can do this: https://www.wired.com/2012/09/broad-sustainable-building-instant-skyscraper/

  • $\begingroup$ If you're already using helicopters, and the wind is calm, you don't need cranes. In fact, cranes would make helo operations worse: Chernobyl. The limit will be how many helicopters you can transit in and out of the worksite without contention / having a Desert One situation. Because then, you fail. You have no chance of recovering from two crashed helicopters and a bunch of module damage in 12hrs. $\endgroup$ Feb 19, 2017 at 8:02

It's all in the staging

enter image description here src

Consider the usual way these big, fast projects are done: "10 miles of track laid in one day", that skyscraper, freakishly fast railroad bridge replacements (wait til morning Amtrak, replace 800' bridge, let evening Amtrak through). These absolutely depend on advance placement of those materials, and lots of advance site prep. These quick builds are generally stunts, and everything they'll need from modules to tools is already on the site.

If you can't do advance site prep, it'll help to at least reconnoiter the site so you're working from a really good site map. That said, Seabees can do site prep pretty fast. Trouble is, this is linear: first you must reach the site with the prep equipment, then prep, then start to build. Tick tick tock.

Fly sections in requires cutting-edge tech

You need either favorable wind, or helicopters that are really good at automated dynamic positioning. *Another answer proposed delivering the modules to the vicinity and also having a crane. Problems: setting up the crane is still a critical path; helicopters don't play nice with cranes; a safe distance will mean a big messy laydown area.

So the answer is the helicopter is the crane. Build the modules out of ultralight materials - spare no expense. That way you can haul more building per pass. Then you have embedded radio-tech (i.e. Bluetooth) in the modules that talks to the heli-crane about positioning. The automation is to keep the humans out of it, because when humans are involved, Desert One happens.

Upside: nothing touches the ground except the building and site-prep team. Their gear can be landed inside the building's footprint, and a space in the first floor can be dropped over the construction gear.

If you're able to do all this, you may also be able to revive the old super-helicopter designs like the Mil Mi-12.

Each module dangles 4 cables (or 2 U-shapes). As the module gets near, workers in the module below (which has an open ceiling) grab each cable and feed it into a pre-installed winch. The winches, talking to each other and the positioning tech, drag the new module down, helicopter and all. The helicopter's up-lift keep cables taut so the module comes down square. Once the module is locked in, the helicopter slacks its cables, drops load, and goes to get the next module.

Keep in mind, this is not what engineers do. They think carefully, and take the time needed to be safe. Speed has to be engineered into the design and the robotics.

Haul Road to Hell

You want to go overland? OK. You have a logistics train to get all the materiél to the site. This sounds easy until you mention no roads.

Here's the gotcha with that. If the area is at all civilized and there are no roads between towns 20 miles apart... there'll be a reason for that like a wide river, deep canyon, or truck-eating swamp in the way. Obviously, terrain has everything to do with how you solve this.

So you get your Seabees out there and build the road. The combat engineering isn't necessarily a problem... but this is all happening inside your 20-mile limit, so does it happen "on the clock"? Combat engineers can move pretty fast, but that really depends on terrain and you could find yourself unable to build the road inside 12 hours let alone the building.

There are two ways this can go sideways. First, you can hit complications building the road, and have the entire project run down the clock because it can't get to the site to start. It might be worth having 2-3 separate Seabee batallions working redundantly on parallel roads, so you can zig-zag if needed. Second, you can have a similar, critical problem on the onsite construction.

All of these delays stack. Like how the Empire Builder is always hours late. A 56-hour train run just faces too many chances for a grade crossing accident, traffic delay etc. French TGV runs are on time because their runs are short.

Erection is straightforward, just have the usual jacking crane in the middle of the building and abandon it rather than replace it with elevator shafts.

Alternately, jack the building instead of the crane, using Hulcher bulldozers or built-in jacks to lift the entire extant structure while new floors get slid into the bottom. Let down onto them, latch them in, then jack them for the next floor. Faster and less messy.

Burners come closest

Every year, Burning Man attendees roll in with their crazy structures and plop them down on the virgin Blackrock desert. They are prefabbed (forget about getting any time on machines at TechShop in the month prior), modularized, put on vehicles, dragged in, and set up.

enter image description here 2013. The saucer is 120 feet across. src more

How long? Well for Burning Man official structures (you know, like the Man himself), a week or so. But for some attendees it is pretty much overnight, and if the bigger projects were pressed, they too could get it done in 12 hours.

This is done by geek kids, for fun. Imagine what an advanced military could do.

Fly the building there.

This assumes your building's purpose can be accomplished in a reasonably large airplane or starship. It can look like a building; nobody needs to know the first few floors are nothing but elevator lobby and engines.You build the building at leisure. You only need to land once; consider The 100, where certain former spaceships landed roughly, but continued in service as a building/fortress.

Or just drive it!

Perhaps stretching your meaning... but we build the building, at our leisure, back at the staging area. The first 3 floors are this.

enter image description here source: NASA

On Construction Day, the building is already finished. We start driving whilst the combat engineers sprint ahead of us, blazing the road. At 2.0 MPH, we get there with 2 hours to spare. Since there's only one vehicle passage, there's more time for the combat engineers to tidy up/coverup the obvious haul road, and they don't have anything else to do. The huge tracks can be hidden by fold-down covers.

Obviously this doesn't work with a canyon or swamp, but for a wide flat river like the Platte with good rock beneath it, it might be just the ticket.

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    $\begingroup$ When did I ban staging? I explicitly put staging at a 20 mile radius. $\endgroup$
    – SRM
    Feb 19, 2017 at 5:10
  • $\begingroup$ You did! Sorry! Amended. However, must say... moving massive quantities of materiél 20 miles without roads creates huge challenges that do nearly amount to a ban. You could spend 2/3 of your time getting there. A tank battalion is doing very well to make 35 miles in a day offroad. $\endgroup$ Feb 19, 2017 at 7:11
  • $\begingroup$ true. But when the goal of the story is to have a building spring up seemingly from no where -- as if by magic, with no one outside of the builders aware that it is coming -- that's gotta be in the requirements. $\endgroup$
    – SRM
    Feb 19, 2017 at 14:47
  • $\begingroup$ So is an obvious and very messy haul road out of the question, then? $\endgroup$ Feb 19, 2017 at 15:22
  • $\begingroup$ No. It's the unexpected arrival that matters. I said in question that cleanup within the time limit is a bonus. :-) $\endgroup$
    – SRM
    Feb 19, 2017 at 17:00

I'm actually willing to bet that you can get about 5-6 stories. With new dome inflation methods you can get domes theoretically up to 50m in diameter, and while not a perfect hemisphere, probably reaches above four stories (a full hemisphere would be about eight stories), and could easily be constructed in 12 hours given unlimited material and manpower. You might have some foundation problems though, but I think after a bit of settling you would probably be okay. Especially if you could just set it on top of more concrete- you could use fast setting stuff (brand name is quikrete) and probably be fine for a while. It wouldn't have incredible stability or easy access, but you'd have a "building".


To expand on one of @Swier's ideas, create a hover-craft-building. There were some ideas of suspending buildings during earthquakes on a cushion of air with fans and a skirt Well, I know what that is, it is a hovercraft.

Obviously you have to scale up to support a larger building. The sears tower weights 222,500 tons and has a ground footprint of 225x225, or 7.3M square inches. Thus you need to have a pressure of 61PSI. That is...a little high. Obviously the solution is to make the base bigger. Making the base 6644 feet square (44M square feet) yields a much more comfortable .2PSI--I'll assume that such a base can be constructed that transfers the tower weight evenly over the entire area.

Instead of (or in addition to) using a traditional skirt, you can use a solid reactive skirt that raises or lowers slats to a few mm of the ground. If you need to go over a tree or something, then ignore the tree and the inertia of the skyscraper will shave the tree right off (assuming strong slats). Maximum slat height would be the maximum delta height between the front/back/left/right corners over the desired course. But just like a normal hovercraft, you can go right over water. Actually, with an airlock approach (multiple skirts on the leading and trailing edges) you could even go over the odd house--raise the outer skirt until you cover the house, then lower the outer skirt and inflate. Then raise the inner skirt and the house will be just fine.

The last problem is keeping the building upright. Also easy. Just get some huge gyros going and mount the thrust fans at the center of gravity (or anyway have the aggregate thrust axis match the center of gravity since you wouldn't want a single thrust point).

Not very stealthy the other party is deaf and lacks a tactile sense--if they do you can just pop your building up in the middle of town, maybe. If you construct the base of the building on a jig that has the same ground profile and contour of the target location, then you can just sit it right down and be done. 1450 ft (plus base height) in 12 hours--I'll assume the building can get a running start to cross the starting line 20 miles out and the bow-side could be studded with JATO rockets to slow down. Probably you could cover more than 20 miles--perhaps even the ~50 miles needed to hide the initial building of the structure--in 12 hours. 4.2MPH initial velocity should do it.

For another idea, SpaceX has shown that they can land a 150ft "building" on pretty much any flat surface within minutes. A little more engineering work could increase landing gear size and reactiveness (to not need level ground and to not need ultra-hard ground). Probably the biggest problem would be the flames and blast pressure which could dig a hole that the landing gear couldn't react to. Fortunately, we can fully prep beforehand including a laser ground map so we could have pre-formed jigsaw pieces of ceramic tiles with different heights with precise destination locations to form a level heat resistant landing pad. With helecopter deployment and a lightweight jig to help guide the pieces in place, I bet from choppers crossing the starting line (20 miles out) to MECO after landing can be done in under 20 minutes (though the last men on the ground putting the pad together better wear their asbestos long underwear since the rocket will be launched prior to the pad being complete) with a 10% chance of success (and lower chance of zero fatalities). Use parallel construction to get sufficient reliability. Given 12 hours, you can probably get normal SpaceX reliability with normal SpaceX risk of death.

Another non-stealthy construction technique. But much cheaper than the first one.

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    $\begingroup$ Nice thinking, but answer should be an answer. This is not. If post you age referring to gets deleted, this one will make no sense. $\endgroup$
    – Mołot
    Feb 18, 2017 at 8:35
  • $\begingroup$ I like the out-of-the-box thinking, but for this question, I was actually looking for more in-the-box thoughts. Keep this in mind for "how do I build a flying citadel?" :-) $\endgroup$
    – SRM
    Feb 18, 2017 at 23:42
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    $\begingroup$ The "jumbo hovercraft" solution has a big problem: on such large scales, rigid objects aren't rigid. You can't count on the stiffness of the structure to keep your hundred thousand propulsion fans moving forward at the same speed, you need to monitor their position individually and adjust power output accordingly. $\endgroup$
    – Mark
    Feb 19, 2017 at 20:49
  • $\begingroup$ @Molot: I'm not sure what you mean. I reference two posts. One post is the one that describes suspending a building on a cushion of air for earthquake protection--and the link text gives that very description. The second post is the one that gives the weight of the Skyscraper--and the link text gives the weight. Exactly what should I include further in case the backing links disappear? $\endgroup$ Feb 20, 2017 at 16:00
  • $\begingroup$ @Mark: Very good point. I vaguely referenced using multiple thrust engines to avoid folding the skyscraper in half with all thrust at one point, and I entirely handwaved around the problem of attaching (and distributing the weight of) the skyscraper to the base (which I recognize as a significant engineering problem), but you are absolutely right that a thrust control system would be needed to stabilize everything vertically and horizontally and a square mile base itself would be very hard to keep together. $\endgroup$ Feb 20, 2017 at 16:06

If you look at a container port or a large container ship you will have a fair idea ....

There is no difficulty with building accommodation modules in a factory elsewhere and connecting them rapidly on a development site. How rapid is rapidly, depends on the economic justification for hurrying. Above a certain speed the necessary logistics will cost more and disrupt the surrounding community more. Speed will also worsen any snafus. So why rush?

The greater problem is the infrastructure. The building will need electricity, water, and sewerage services. Unless it is a replacement for some similar-sized former development, the visible part of the development cannot happen until infrastructures are in place. This takes longer than "foundations" (which are almost unnecessary if you are building on hard bedrock). You will also need cranes and other heavy construction equipment delivered to the site and prepared. Oh, and a workforce who know what to do.

I've often heard it asked, what are the builders wasting their time on between bulldozing the grass and trees, and starting to build the houses? Infrastructure (and foundations) is the answer. (wet weather can bring such work to a complete halt. You can't build the drains you need while you really need the drains!)

I have watched a modular student accommodation building grow at about a storey per week-end. Week-days, no visible work was happening. It was an inner city site and the traffic disruption caused by lorries delivering modules on weekdays would have been quite horrendous. So they didn't.

  • $\begingroup$ This answer appears to be "no building can be built overnight." Am I reading that correct? $\endgroup$
    – SRM
    Feb 18, 2017 at 23:44
  • $\begingroup$ I disagree, infrastructure doesn't need to be buried, it can be in the first floor modules. $\endgroup$ Feb 19, 2017 at 8:05
  • $\begingroup$ @Harper sewerage / drains? Sure you can bring it all together in a big pipe prefabricated, but you have to have a pipe from there off the site. You also need capacity in the area's sewers and sewage treatment works. Similarly capacity to supply water without undue pressure drop, electricity without any overloads. And you need drainage for when it rains hard. $\endgroup$
    – nigel222
    Feb 19, 2017 at 10:08
  • $\begingroup$ @srm pretty much right. The building can appear pretty damn fast, but that's the final outcome of a lot of prior planning and logistics. $\endgroup$
    – nigel222
    Feb 19, 2017 at 10:13
  • $\begingroup$ @nigel22 Since I've seen a 1-story home done in a day, including running water/sewage and electrical to that home, I'm going to disqualify this answer. You make some good points about the difficulties, and that may well limit the size to very small, but my experience says the threshold is at least non-zero. $\endgroup$
    – SRM
    Feb 19, 2017 at 14:52

"The tower of Babylon" was erected in Black Rock City, NV during Burning Man festival 2008.

It is 10 floors, 100ft tall. It was erected in 3.5 days with only one crane and 5 construction workers. It was built on the virgin land of Black Rock desert and was disassembled ~week later in 1.5 days, leaving no trace behind.

I assume that with additional resources this very building could be built faster, and similar building of the same technology could be bigger.

  • $\begingroup$ This answer was useful by suggesting that large construction was possible, but I already suspected that from the examples I gave in the question. This answer didn't provide enough detail to gauge how much could be done in one night. Thus I did not consider it to be "in the running" for final answer -- but thank you for the supplemental information. $\endgroup$
    – SRM
    Feb 19, 2017 at 14:59

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