Underground City Design (Non-commercial Collaborative Project)

Want to collaborate on an underground city design?

The idea is to design a new country that’s mostly located underground, except for small surface cities to connect the imaginary country to the outside world. All area surrounding the small cities would belong to another country, but the small cities would be their own interconnected country. Here’s a rough sketch of my idea. Feel free to tell me what you think of the idea. Remember, this is just a rough sketch.

Underground Country.skp (671.4 KB)

That’s my basic plan for the new country. Basically, it’d be the same design as other countries, except underground in a 3D street network (rather than a 2D city street grid). I think a good place to start is designing an individual city. Since this is such a big project, I think making it a community effort would help a lot. Also, valuing a variety of different peoples’ opinions will improve the city design. I’ll be doing 3D modeling and rendering for this. You can see some of my previous renders here and here (P.S. I’m just a hobbyist). But if anyone shares an interest in city design and wants to help, then you are welcome to join! This project is for fun and is not intended to be actually built, but I’d like to make the final design as realistic as possible.

Limitations (feel free to change/add):

Max depth: 1.5 miles - 2.4 miles

Max size: Undecided, but maybe 20 miles x 20 miles x 2 miles

File size: 50 MB

Problems & solutions to living underground (feel free to change/add):

  • Lack of light

    • High powered sun-simulation lights
  • Oxygen

    • Ventilation from surface

End goal (Feel free to change/add):

  • Low-medium level of detail 3D model with no interior designs for buildings. Building exteriors modeled and city areas labeled based on their purpose and location name.

  • One single city with tunnels pointed outwards from the city to indicate it’s connected with other cities.

  • Some pages of artistic 2D plans and renders


The community can exchange and improve each others’ models. When the file size gets too big for the forums, then we can use the 3D Warehouse to exchange models. Anyone’s contributions, no matter how small, are appreciated! But let’s try to keep it on-topic and constructive. And everyone is welcome to join in on the fun.

I’m a regular on this forum, so you can contact me through PM & I’ll probably get back within a day or two.

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I researched what general types of buildings are in cities, then sorted them into Maslow’s hierarchy of needs to help me understand which buildings are most important for city design.


  • Water management

  • Farms

  • Houses

  • Clothes stores


  • Restaurants

  • Power

  • Medical

  • Military

  • Industrial

  • Government

Belongingness & love

  • Parks

  • Civic

  • Religious


  • Schools

  • Stores

  • Businesses


  • Parking

  • Storage

  • Transport

  • Infrastructure

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Is each underground city supposed to be self-sufficient? Perhaps there is an underground industrial area with only factories and other nasty stuff. A separate underground city for living and eating. Yet another for amusement … possibly an underground lake with beaches. All interconnected by high-speed tube lines to each other and the surface.

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You may want to consider this technology…

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The country(s) on top of your country may declare your country illegal depending on whether their real estate jurisdiction is like the United States’ or UK’s.

There have been efforts in history to put countries (partly) underground but have luckily failed.
I wonder about the diplomatic relations of the underground government with their neighbors, how can they be convinced that there are no obscure doings?

I could imagine living in a closed arcology (city in one building) has social implications that need to be researched in a pilot project (similar to the Mars travel simulation).

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What would be the most efficient power source for an underground city? I was thinking geothermal energy sounded promising because underground cities are closer to the magma than surface cities. Other sources I’ve considered are hydroelectric (if there’s any moving water underground) and hydrogen power.

I’m thinking about making use of natural caves & also designing man-made caves with a more geometric shape.

Yes, but it also would trade goods with the surface country.

The country would have to be made respecting the neighboring country. The new country would need permits and everything. One reason making a new country interests me is experimenting with different types of government, such as technocracy (the government or control of society or industry by an elite of technical experts) or something. I think it’s important that the government uses science and always does what’s correct… Or at least makes the most educated decisions possible.

I’m making the cave now and uploaded the work in progress model, so people can use it if they want.

Edit 2:
Some progress. Added textures, working on placing stalactites/stalagmites. This area is going to be the residential/business area, then another two caves will be the farming area and industrial area.

What style of architecture would look good in a cave? I was thinking mars-colony style architecture might look cool, maybe theme park style, but I’m totally undecided. Maybe space age futuristic? Edit: I decided high tech futuristic minimalist with organic architecture. Black, shiny white, and red.

Can someone help me find a 3D model of a cave system with dimensions kinda like in the video? I want to make my cave a realistic shape and size.