In history a city is defined as a human settlement governed by functions and endowed with a stable structure and a reference territory. Cities can have different geographical locations. For example, they can be laid out on a coastline, or lie down along a river or wedged in a mountain valley. Cities were born and developed by strengthening their cultural identity; unique and recognizable bodies provided with a microclimate, a smell and a precise atmospheric quality.

In 1991 in a working seminar the Dutch sociologist Saskia Sassen coined the term "global city". While the term "megalopolis" refers to cities of enormous dimensions, a "global city" is instead a metropolis of great power, with a considerable internal hierarchy and significant external influence. A strategic economic and commercial centraliser where particular skills and resources are increased. Cities of different nations and continents that have much in common with each other and end up resembling and homologating with each other. The transnational ongoing processes make the contemporary cities theaters where the conflicts and contradictions of capital globalization are consummated.

A new spatial organization of economics and IT (Information Technologies) finance redesigns an unprecedented form of urban society, opening up deep questions about the environment, social integration and the identity of the cities themselves.