Read The World Outside Storyline:
In the 24th century there are 75 billion people on earth, and they live in monstrous high-rise buildings that are worlds unto themselves. Over 800 stories tall, the "Urban Monad" allows everyone to live in a Utopia. Or is it a Utopia? This story was later expanded into an urban SF novel called "The World Inside." Hugo Award NomineePages of The World Outside :