large social estates known as cités and the beginning of the business district La Défense. A comprehensive express subway network, the RER, was built to complement the Métro and serve the distant suburbs, while a network of freeways was developed in the suburbs, centred on the Périphérique expressway encircling the city.
Since the 1970s, many inner suburbs of Paris (especially the northern and eastern ones) have experienced deindustrialization, and the once-thrivingcités have gradually become ghettos for immigrants and experienced significant unemployment. At the same time, the city of Paris (within its Périphérique expressway) and the western and southern suburbs have successfully shifted their economic base from traditional manufacturing to high-value-added services and high-tech manufacturing, generating great wealth for their residents whose per capita income is among the highest in Europe. The resulting widening social gap between these two areas has led to periodic unrest since the mid-1980s, such as the 2005 riots which were concentrated for the most part in the northeastern suburbs.
A massive urban renewal project, the Grand Paris (Greater Paris), has been launched in 2007 by former French President Nicolas Sarkozy. It consists of various economic, cultural, housing, transport and environmental projects to reach a better integration of the territories and revitalise the metropolitan economy. The most emblematic project is the construction by 2025 of a new automatic metro which will consist of 150 km rapid-transit lines connecting the Grand Paris regions to one another and to the centre of Paris.
Nevertheless, the Paris metropolitan area is still divided into numerous territorial collectivities and their fusion into a more integrated metropolis government, although sometimes discussed is not on the agenda. An ad-hoc structure, Paris Métropole, has however been established in June 2009 to coordinate the