The Caves of Steel by Isaac Asimov is a story set on earth far in the future, in around the year 3300. Most of the story takes place in either New York City, the largest city on Earth, or Spacetown, the colony set up by inhabitants from one of the outer worlds. The two communities really show the different ways of life adapted by their population. Earth has become so over populated that the cities are now built mainly underground, just like caves of steel. The Spacers are descendants of Earthmen who left the Earth to live on the other planets. Their colony is a series of large domes with lots of space, just like when they had all that area on their other planets. Earthmen distrust the Spacers and the Spacers feel that the Earthmen are full of diseases that the Spacers had gotten rid of long ago...