Chicago has approved the construction of what will be America’s tallest building. “The design for the $550 million tower, which was breathtaking but hardly flawless when it was introduced last July, has taken some important steps forward, both in the sky and along the ground. Now here’s the trend part of the story: If this tower and Jeanne Gang’s sensuous Aqua high-rise both get built, Chicago will be running a clinic in the new aesthetic possibilities offered by skyscrapers that are places to live rather than work.”