Building Utopian Underground Cities

Mexico City Earthscraper design by BNKR Arquitectura - https://archello.com/pt/project/the-earthscraper

Underground cities shouldn’t just be dark and boring holes in the ground, they can be expansive and well-lit feats of engineering and art.

They can utilize clever ways of letting in natural light and bouncing it around the cave. This can be accomplished via a mixture of creative ways to use everything from large and small openings, reflective materials, geothermal sources, bioluminescent lifeforms, and so on. Let’s drill down on some of these a little deeper.

Outside of organic caves, I imagine the three main types of arrangements for artificial cave structures would be as follows:

• Reverse pyramids These would be wider at the top (ie the reversed ‘base’) of the pyramid, or better yet: ziggurat, to let in as much light as possible from a giant hole in the ground (ie their sky). And each level would step in closer and closer so as not to be obstructed by the level above. Perhaps most residences would be situated along the north and south sides to maximize sunlight at all times of the day. While the east and west sides could be used for things that don’t need as much light, or don’t need unobstructed light at certain times of day. These cities could have a mix of stairs, vertical as well as diagonal elevators, escalators, cable cars, and even slides/ramps! (Note! I was trying to find some imagery that I remembered seeing years ago and was not able to find it, but in that process I stumbled across the term ‘earthscraper’ for this very concept! Granted, a lot of those designs go far deeper then I’m proposing here. I think a skycraper is not necessarily the best structure to emulate underground, since skycrapers themselves tend to uphold a hierarchical view of the world… but nonetheless, I wanted to note that people have begun exploring this idea!)

EcoCity2020 by AB Elis ltd - https://www.evolo.us/eco-city-inside-a-one-kilometer-crater-in-siberia/

Inside of EcoCity2020 by AB Elis ltd - https://www.evolo.us/eco-city-inside-a-one-kilometer-crater-in-siberia/

• Large tubes These would have at least two large openings at opposite ends. They allow for a more horizontal city constrained within something like a mountain or old lava tubes or even old valleys. They should be aligned in an East-West direction to maximize light. Perhaps most residences would be around the entrances, while warehouses and things that don’t need much/any light could be in the center. Vertical structures would likely need to be strictly limited to ensure light can reach as deeply as possible.

Lava tube Martian city found in this research paper - https://www.researchgate.net/figure/nternal-view-from-of-the-the-lava-tube-colony-from-the-bridge-connecting-the-vertical_fig19_365034155

Below Freezing by Shane Powers and Linjie Wang - https://www.humanmars.net/2020/09/underground-oasis-in-martian-lava-tube.html

• City-sized caves These would have just one large opening along a side, allowing for a more typical city, but once again, the residential type buildings would be situated near the ‘cave’ entrance with the other structures along the back wall. The size and orientation of the opening would be the main design constraint for urban planning.

Cliff Dwellings of Mesa Verde - https://www.nps.gov/media/photo/gallery.htm?pg=1978152&id=FF496A0D-155D-451F-6780618AC2528471

Cliff Dwellings of Mesa Verde - https://www.nps.gov/media/photo/gallery.htm?pg=1978152&id=FF496A0D-155D-451F-6780618AC2528471

Regardless of the overarching structure of the city/underground environment, there are a number of ‘features’ that would be good for any subterranean city to have. All of these assume some cross-over with ventilation as well.

Ample Light

Underground cities should be built around large openings as the centerpiece and main source of natural light and/or some other method of creating a very well lit environment. They can utilize reflective materials made artificially, or derived from whatever shiny rocks make up their substrate, to bounce light around liberally.

They could also use mirrors, large and small, to make the space feel larger and more open. Such as in alley ways or large dome structures or even windows such that they reflect light and scenic views from above ground all the way into rooms underground.