City of Stone
Bizarre but true, the Earth is poisoned. To keep a large number of people alive, we released gases into the atmosphere, which in a few decades will make a poisonous cocktail together with the other chemicals we gifted nature.
I'm in the city of those who left Earth to live in a spaceship above it. They live better, but not as well, as far as I know. A relatively heterogeneous population of 80,000 people from a city of 1,200,000 inhabitants was selected.
Although genetic information can be stored in a small space, keeping humanity alive is necessary, as I was taught. They have to remake the planet in a couple of millennia and also preserve a living culture we cannot replace.
For whom these monuments were built, us or them, I am not sure. Maybe for those new colonists. Every person who has left Earth stands immortalized in stone, depicted in a typical moment of their life. There stand the name and contact number of that person. They are the forgotten heroes who still live, and we are walking corpses, as I increasingly believe.