Building a city on Mars will be extremely hard, as it’s the first extraterrestrial planet we’re going to terraform. But by the time we have Mars and start terraforming Venus, we’ll just say: /goal Make Venus Great Again! And trillions of self-replicating humanoids will tirelessly work on the surface of the planet, cleaning up the remaining CO₂, breaking down the atmosphere, mining the crust, building factories, and magically transforming Venus into a third home for humanity.(Chun)