Essay: Cities, cradle of modernity Cities are the cradle of our social, economic, cultural and scientific development. During millennia, the emergence of cities has been related to the evolution of society. Since around 3,500 B.C. in Mesopotamia (now south of Iraq) was established the first city, Uruk, where humanity left to be nomads and became sedentary for a better life and to contribute to produce wealth. Nowadays, the cities constitute a window of opportunities, where you can get a job, school, entertainment, technology, health services, sports. For talented and young people, the cities are an opportunity for professional development and for industry, a door for a competitive world. It is undeniable problems caused about overpopulation in the cities: pollution (air, visual, noise), social and economic inequality, crime, environmental effects, etcetera and physical and mental health issues. Despite that, the features of the cities represent too the opportunity to correct the effects of lost values, nature conservation, and cultural identity. With challengers about different types, the cities are a cradle of knowledge too, and it is possible to think about a chance to improve the civilization of our time.