The document discusses the rise and development of cities globally. It describes factors that contributed to urbanization like improvements in agriculture, transportation, and industries. Models of urban growth patterns are presented, including concentric zone, sector, and multiple nuclei models. Challenges faced by large cities are outlined, such as generating revenue, urban decay, and poverty. Environmental issues in global cities like overpopulation, resource depletion, and pollution are also summarized. Finally, some of the largest and most influential cities in the world are listed.