With the world’s population at 7 billion and counting, a real challenge is posed to city and urban planners, architects and engineers: how to design and construct sustainable and intelligent cities with booming populations. Though difficult, innovative solutions abound. In partnership with architects with a flare for sustainability and like-minded engineers to build these structures, urban planners such as Alex Steffen and Sharon Nunes see real potential for smart, efficient cities. Outside of cities, engineers are dreaming up efficient solutions to such problems as water filtering. Change is in the air. Its up to all of us to channel our inner Captain Planet to make a difference.