It’s physical size, permanence (lasts for 200+ years with extensions possible) and cost per unit area (cheap enough for middle class people), safety, no sea motion, pleasant land to live on, strong foundations for large buildings, robustness (not sensitive to one small mistake)
You don’t need to produce food, you don’t even need to produce physical goods. But you do need a population of 1 million people who are there permanently and call it home.
It’s physical size, permanence (lasts for 200+ years with extensions possible) and cost per unit area (cheap enough for middle class people), safety, no sea motion, pleasant land to live on, strong foundations for large buildings, robustness (not sensitive to one small mistake)
You don’t need to produce food, you don’t even need to produce physical goods. But you do need a population of 1 million people who are there permanently and call it home.