Cities are those concentrations of people, and things, without which there couldn't be civilization
The modern city, made possible by technology, is not to be confused with those concentrations, going by the same name, that existed before the invention of the steam engine, which allowed food and other goods to be brought from further and further away. The other invention that permitted the creation of the modern city, is the telegraph.
All refinments of transportation and communications technology, including the internet, have only speeded up the growth of the modern city to the point where it has become another of the dinosaurs of the modern era.
The life of the city has been investigated by Jane Jacobs.