In a futuristic sci-fi world (galaxy?) I'm building, warfare has become highly regulated and commercialized. When two corporations meet on a deserted planet to do battle, they're followed by all sorts of ships: from weapons dealers to mercenaries, everyone wants a slice of the action.
But the biggest and perhaps craziest of them all is the fleet of colonists. Protected by the laws of pseudo-omnipotent post-mortals and driven by the promise of hungry soldiers with full wallets and mountains of scrap metal, these colonists descend upon the battlefield like vultures, building up a city of restaurants, hospitals, brothels, and refineries in a matter of days.
This raises my question, what's the fastest way to put up a city like this? Assume the colonists are about a million strong, and have all the materials they need safely in orbit at the start. They need to get these materials down to the planet, assemble them, and have them in working condition as quickly as possible.
Assume near-futuristic technology, so no transporters, replicators, or magical portals to the alternate dimension of Amish housebuilders. However, energy is effectively infinite and incredibly cheap due to fusion reactors.
Also assume the planet in question is Earthlike- soil, water, minerals in places you'd expect them to be, and a wide variety of terrain formations.
I want this city to outlive the war, and eventually become a permanent settlement. The idea is to use the war to gain some initial capital while the sustaining infrastructure is developed, so I don't want all the buildings to blow away in the wind once the soldiers leave.