Planners and architects now agree that to improve the social and environmental condition of cities the top priority is to cut car use. They say zero-emission cars running on electricity or burning hydrogen are not enough. “Automobiles still require massive networks of streets, freeways, and parking structures to serve congested cities and far—flung suburbs,” says Richard Register, founder of the nonprofit campaigning organization EcoCity Builders in Oakland, California. What is needed is a wholesale rethink of how new cities are laid out-and how existing ones expand-to minimize the need for cars in the first place. One way of achieving this is to build cities with multiple centers where people live close to their work in high-rise blocks that are also near public transport hubs. In parts of the world this is already taking shape.