What would underground cities look like?

Question

I'm worldbuilding an underground world, networks of massive caverns and caves stretching throughout the earth. In many of these exist whole races and species and the like who have built their own civilizations down there. While it is a fantasy world, I do want to base as much of the architecture, structure, and other such details on realistic concepts. Things they'd account for, for instance, would be earthquakes, cave ins, the shifting of tectonic plates, potential splits in the ground, air flow, flood control, temperature control, what kinds of stones/metals they should use, etc.

Resource wise, they'd have abundance of stones and assume they make their homes near sources of water as well as mineral veins, and either near vegetation (mushrooms, algae, mold, and any plants that can survive/thrive on artificial lights) or bring said vegetation to them to farm. They'd have a minimal amount of wood, especially the deeper they went.

I'm researching where I can, but I wanted to check with an expert on these subjects to get as accurate a depiction as I can.

So yeah. What would the architecture of underground cities look like for the most part? Would they have buildings and cities in the middle of the cavern? Would the buildings be dug into the cave walls? Would their pillars and structures have soft or gravely bases to help with shock absorption or would that do more harm than good? What would their general layout be? What sort of defenses might they have against intruders?

Answer 1

Think of a world beneath the surface, where the hum of the earth itself is a constant, comforting backdrop to the rhythm of daily life. This underground city is a marvel of human ingenuity, a seamless blend of practicality and aesthetic beauty.

The grand archways and large tunnels, lit by the soft golden light mimicking the sun's warmth, greet you upon entering this subterranean realm. Architecture can be both sleek, modern lines and organic shapes devised to bear loads of pressures of the earth above. Rising from the cavern floors, like so many stalagmites, buildings are joined by bridge after bridge and walkways suspended in the air, all three-dimensionally woven as life.

Precious natural light here is seldom to be seen but is piped in by clever mirror and optical systems from the world above. It feeds the lush growth of vertical gardens cascading down walls, filling spaces with bright greenery and sweetly perfumed flowers in bloom. Hydroponic farms grow crops in reserved areas, creating freshness and at least one sense of openness in this confined world.

The air is fresh, due to sophisticated ventilation systems drawing from the earth for geothermal energy and regulation of temperature, ensuring a constant supply of oxygen. These whisper softly in the background to further create an atmosphere of tranquility.

It's transportation-a whole art form unto itself: sleek electric shuttles that zoom with silent ease through subterranean highways, while at street level, moving sidewalks and elegant footpaths invite every kind of exploration. This city derives its energy from mixed renewable sources, harnessed both from geothermal vents and transmitted solar energy for sustainability and resilience.

The living spaces are cozy and futuristic, with smart home technology seamlessly worked into every apartment. These homes maximize space, offering comfort and functionality while maintaining openness and freedom.

Public spaces are alive with activity and culture: parks with artificial skies that change from dawn to dusk, theaters that house live performances alongside immersive virtual reality experiences, and sports facilities that keep residents active and involved.

Water and waste management systems speak to human ingenuity, reusing and re-purifying resources to maintain a self-sustaining ecosystem. Community centers, libraries, and places of worship allow residents to connect, reflect, and find solace.

In this underground utopia, life thrives beneath the earth's surface-a true testament to the strong will of humans and their never-ending quest for a new frontier. It's a place where possibility is endlessly rewritten and the heartbeat of the earth is a thing felt with every moment. ????✨