Modern cities have recently evolved as centres for material and intangible exchanges and this obliges us to rethink the urban scene. The passing from the industrial era to the new age of information has rendered obsolete the models envisaged by Max Weber, Georg Simmel and Walter Benjamin. Basing her argument on the typology put forward by Saskia Sassen, Barbara Freitag sketches out the different profiles of contemporary cities. Urban centres are now defined by the level, scale and intensity of the exchanges to which they give rise. On the first level is the global city, nerve centre of the globalized economy (Tokyo, New York, London …) and capable of challenging the power of the state. On the second level are the megalopoles (Mexico, São Paulo …), which are only prevented from joining the ranks of the global cities because much of their population is excluded from the global economy. Next come the metropoles, cities like Paris (‘19th-century capital’), which have retained a way of life global centres can no longer provide. However, most of the world's population is concentrated in the peripheral boroughs of the information society's global economy. It is for the sake of this population that attention must be paid to the transformations endured by 21st-century cities.