A Giant Spinning Cylinder for a Million People: Scientists Reveal Their Most Ambitious Habitat Concept Yet

Imagine walking through a city where the horizon curves upward instead of disappearing into the distance, where sunlight pours in through angled mirrors rather than an open sky, and where lush green parks stretch not across the ground, but along the rising interior walls of an enormous rotating world. This is not a scene from a sci-fi blockbuster. It is a new large-scale engineering proposal developed by a team of astrophysicists and space architects: a massive, rotating space cylinder designed to host up to one million permanent residents.

While the concept draws clear inspiration from the classic O’Neill Cylinder imagined in the 1970s, the new proposal uses technologies that did not exist even a decade ago—self-building robots, closed-loop ecological systems, ultra-light composite materials, and AI-driven environmental control. According to the authors, these advances shift the idea from speculative fiction toward a long-term realistic project.

Artificial Gravity Through Rotation

The foundation of this megastructure is simple in theory but monumental in practice: rotation. The cylinder, roughly 30 kilometers long and about 6 kilometers in diameter, would spin at a carefully calibrated speed to create artificial gravity through centrifugal force. To residents walking inside the structure, gravity would feel almost identical to Earth’s. Children could run, people could cook, work, and live without the health issues associated with weightlessness.

The inner surface of the cylinder would serve as the primary living area. It would be divided into discrete zones—residential districts, agricultural regions, transportation corridors, recreational spaces, and even preserved natural areas designed to mimic Earth-like ecosystems. Think of hiking through a conifer forest or jogging along a riverside trail, all while knowing that the “ground” curves up toward the sky on both sides.

A Self-Sustaining World

One of the most critical engineering challenges is building a habitat that is almost entirely self-sufficient. To achieve this, researchers propose a mix of next-generation technologies: vertical farming towers, advanced hydroponic systems, algae and bacterial bioreactors to recycle organic waste, and highly optimized water purification cycles.

According to preliminary calculations, approximately a quarter of the cylinder’s inner surface would be dedicated to food production and environmental regeneration. With controlled climate zones, optimized light cycles, and efficient water reuse, these agricultural sectors could produce enough vegetables, grains, fruit, and plant-based proteins to support a population the size of a major city. In fact, researchers point to the example of modern Antarctic research stations, where closed-loop systems already provide fresh produce year-round in one of the harshest environments on Earth.

The external surface of the cylinder would be covered with state-of-the-art solar arrays, supplying energy for life support, manufacturing, transportation, and environmental control. A system of giant mirrors would reflect sunlight into the habitat, creating an artificial day-night rhythm essential for human health and agricultural productivity.

Where Would This Giant Cylinder Be Built?

Scientists are considering two primary locations for such a structure: low Earth orbit and the Earth–Moon L5 Lagrange point. The second option appears more attractive due to its gravitational stability and reduced fuel requirements for maintaining position. It also offers strategic access to near-Earth asteroids, which could supply most of the raw materials needed for construction.

The building process would rely heavily on autonomous robotic swarms capable of mining, processing, and assembling structure components directly from asteroid material. Instead of transporting heavy resources from Earth, the majority of construction could happen entirely in space. Researchers suggest that the full project might take several decades—but its completion would mark the beginning of a new era of permanent human life beyond Earth.

A City That Feels Like a Civilization

Inside the cylinder, life would look and feel familiar but subtly different. Urban districts would feature mid-rise residential blocks, communal workspaces, plazas, schools, and cultural centers. With no storms, floods, or seasonal extremes, infrastructure could be optimized for comfort and efficiency. Parks and natural preserves would help maintain both ecological balance and psychological well-being.

One of the most striking visual effects would be the horizon itself. Instead of fading into the atmosphere, it would rise steadily upward until it curves overhead—revealing more homes, forests, and fields inverted in the distance. Early test renderings show children pointing upward in astonishment as they realize that the “sky” they see is actually another district of the same world.

A Blueprint for Humanity’s Spacefaring Future

The proposed cylinder is more than a habitat: it is a prototype for a new branch of civilization. With its own economy, culture, governance, and identity, it could become a blueprint for future space settlements scattered throughout the solar system.

Yes, the project remains theoretical and demands breakthroughs in engineering, material science, and international coordination. But for many researchers, it represents a logical next step. If humanity is to move permanently beyond Earth, we will need not just rockets and stations, but entire worlds—self-contained, sustainable, and built for generations.

And perhaps, sometime within the next century, the first million humans to live off-planet will not step onto Mars or the Moon, but into a vast, rotating cylinder where the horizon curves toward the stars.