is by Robert Silverberg, and isbn: 0743487230. He is a writer i have read before (book of skills) and this book from 2004 deals with a world of billions living in many single structures with a few farmers living a a simple life.
It details the lives of five people whom have a perspective on there lives in one building. some fear change,others see things as they are, and one who fails to have a happy ending
5/5 bananas – worth a read