The Caves of Steel (Isaac Asimov, 1954)

In this novel, Isaac Asimov first introduced Elijah Baley and R. Daneel Olivaw, who would later become his, and more so his readers', favorite protagonists. They live roughly three millennia in Earth's future, a time when hyperspace travel has been discovered, and a few worlds relatively close to Earth have been colonised — fifty planets known as the "Spacer worlds". The Spacer worlds are rich, have low population density (average population of one hundred million each), and use robot labor very heavily. Meanwhile, Earth is overpopulated (with a total population of eight billion), and strict rules against robots have been passed. The eponymous "caves of steel" are vast city complexes covered by huge metal domes, capable of supporting tens of millions each. The New York City of that era, for example, encompasses present-day New York State, as well as large tracts of New Jersey.