We often say that climate change threatens cities. But if we are being more honest, what is truly being shaken today is not the city itself, but the way humans have lived. We are living longer than ever, holding more powerful technologies than ever before, and yet being pushed into the future without having built the social, spatial, and ethical structures capable of absorbing that speed. Climate change, the advent of a longevity society, and technological transition are not separate problems. They amplify one another and converge into a single question: How can humans continue, all the way to the end?

Sim Eternal City begins with this question. It is not a proposal for building just another city. It is a storytelling framework that uses the city as a medium to redesign human sustainability. We are not satisfied with imagining a safer shelter or adding a more efficient system. Instead, we ask: in an era when cities themselves can disappear, what kind of structure can hold together the full span of human life—life, work, care, memory, and death—without breaking apart?

The ten points introduced here are neither a feature list nor a technology roadmap. They are coordinates for thinking—ways to take one question apart and reassemble it from different angles. Why define the first citizens as elderly people displaced by climate collapse? Why call humanoid robots “citizens”? Why does this city speak of coexistence rather than escape? Why design a city around an 18-minute rhythm? All of these questions ultimately lead to one deeper inquiry: To what extent can a city take responsibility for the final chapter of human life?

The best way to read this text, therefore, is not to treat Sim Eternal City as a finished answer, but as a framework of questions you can apply to your own city and your own life. These ten points are not a conclusion; they are a beginning. In the age of climate crisis, longevity, and technological transition, they form a map for asking—together—what shape human continuity should take in the cities we inhabit today and the cities we have yet to build.

1. Sim Eternal City is a future city storytelling framework that asks how humans can continue to the very end in an era where the existential crisis triggered by climate change overlaps with the rise of a longevity society and technological transition.

2. The first citizens envisioned by this city are elderly people who have lost their homes due to climate-driven urban collapse. The second citizens, who will build coexistence with them, are defined as humanoid robots—recognized here as “citizens.” On the premise of coexistence between these two, the city redefines and designs invisible assets such as connection, memory, and preservation as core urban infrastructure.

3. Sim Eternal City is neither a dystopian escape plan nor a substitute city, and it is not a second Noah’s Ark. Rather, it is a parallel urban layer that expands the functional spectrum of the city through the coexistence of the Land City and the Floating City—and a new mode of urban operation that complements existing cities.

4. This framework designs the rhythm of life as an 18-minute city (15 + 3). In the Floating City, 15 minutes completes essential living infrastructure (essential needs), while the additional 3 minutes are dedicated to recording, memory, education, and transmission—an operational unit that connects past, present, and future within a single city.

5. Silver Communialism is a civic economic model that operates on the compact spatial structure of the Floating City. Food, clothing, shelter, and recreation are arranged within close range, combining cabin-based housing with shared living infrastructure. Elderly citizens contribute and are rewarded not through a wage-labor-centered system, but through self-directed work and collective production, while maintaining freedom of choice in consumption and lifestyle.

6. The Life Tree System, located in the city square corresponding to the +3 minutes of the 18-minute city, transforms elderly citizens from objects of care or mere consumers into civic assets who contribute to the maintenance and circulation of the city. At the same time, it serves as a key mechanism connecting the present and future generations of the Land City, designed so that contributions to building and operating the Life Tree become a sustainable income pipeline without undermining human dignity.

7. In existing cities, strong national and institutional constraints make it difficult for citizens to choose their social and economic systems freely. In contrast, the coexistence model of Sim Eternal City allows citizens, by their own free will, to choose, move between, or combine the Land City’s market economy (capitalism) and the Floating City’s civic economy (Silver Communialism).

8. The operation of the city is completed through a compact structure and mobility-centered execution. Movement, delivery, healthcare, and death care are connected through various forms of mobility, and mobility is redefined not as a mere means of transportation but as Purpose-Built Vehicles (PBVs) that carry urban functions.

9. This framework begins its development and validation with the New York scenario, aims to operate a Floating City prototype by 2040, and designs a long-term evolution toward integration at the level of a “Floating Borough” by 2080.

10. At the same time, the framework is intended to spread and be applied so that other coastal cities around the world can create their own hopeful urban narratives in their own languages—and eventually implement Floating City prototypes in reality.