A panel convened by the National Academy of Engineering announced today a list of the most important projects in the world—at least, what would be, were we to figure out how to build them. The 14 priorities range from economical solar power—we only need to harness 1/10,000th of the sunlight that hits Earth to satisfy the world's energy needs—to reverse-engineering the brain and universal access to clean water (see the full list after the break). They're also introducing a slick new website to solicit public opinion. What do you think is the most important engineering challenge for the century to come?