Houses on mobile cranes
If you're building a city from scratch, I think mass manufacturing houses and then transporting them with mobile cranes to the site might actually be economical. There are mobile cranes that can lift that much (eg. http://www.dlbcranes.com/news/cr046-liebherr-ltm-1250-6-1-300-ton-all-terrain-crane-a-smart-choice), and while current houses aren't designed to be lifted from the top, that's probably work-aroundable with reasonable engineering effort. It's still kind of crazy, but the direct and externalized costs of on-site manufacturing are so huge that they might exceed the capital and operational costs of transportation.