" But let us go at the bottom of things: proliferating urbanization outdates the very concept of "town" since, replaced by the agglomeration and conurbation, the town ceased existing "
" If one supposes some perenniality in the current means of transport, if one refuses to waste the available roads and railways, if one takes account of the urbanization which tends to dispute the principle of single centrality, there is no doubt that it is in the judicious treatment of the urban cores... "".... The " urban cores " solution meets this very strong tendency according to which, in our society, one readily seeks a residence at some distance from the urban centres, provided that one can easily reach them when one feels a desire or a need for them ".
R. Auzelle. Clefs pour l'urbanisme (Keys for town planning).
Centrality: Centrality is " the capacity conferred on a town to offer goods and services to an external population ", definition that German Geographer W Christaller proposed in 1933 in his Central Place Theory (1). The concept spread and extended to characterize any place offering service to specific customers; and Manual Castells in 1972 writes that " centrality is the combination at a given time of economic activities, of political and administrative fonctions, of social practice, of collective representation which contribute to the control and regulation of the whole structure of the town ". He starts from the idea that the centre must group the central economic, political and ideological functions. To satisfy these needs supposes the interconnection of geographical places by transport and telecommunication networks. The evolution of town planning starts from the single centrality of a town " to lead to the urban cores of the agglomeration ". (R. Auzelle)
At the same time Francoise Choay said that centrality " .. depends on the capacity of attraction or diffusion of this element which rests on both the effectiveness and the accessibility of the central pole. The element can be an urban centre, a more specialized polarizing facility (shopping, cultural, financial, administrative centre...). Accessibility is a major condition ".
In the European ancient town, generally a Roman town and a town of colonization, the forum is set at the crossroads of the cardo and the decumanus. Place of religion, justice and commerce, it reproduced the model of the forum of Rome, at the same time centre of the town and focus of the public life.
In the medieval town, the organization of space seems confused because it does not proceed of a pre-established plan, but is the consequence of a fine adaptation to topography. On the other hand the functional centrality does exists, around the religious and commercial functions: the church and the market.
Later, in the low Middle Ages in Northern Europe, and in the Renaissance in Italy, the citizens' power is established, it is physically written by a " communal palace ", often equipped with a belfry, and accompanied by a square, in competition with the religious power. This feature remains still clearly today in Paris, with Notre-Dame (5), and the Town hall. Urban creations of this time, country house or new cities of the Renaissance, on orthogonal or radiant level, always wrote the centrality by putting the major place at the center of the street system.
At the end of XIXème century, the construction of the stations in periphery of the town, creates a new place of attraction and exchanges of people, who develops around the district of the station in connection with the centre town. The avenue of the station and the place of the station will be major public spaces which will come to be added to the representation of the centrality. In 1898, English Ebenezer HOWARD, proposes a reform political, economic, and social, that it formats in the " garden city "
The evolution of our urban company towards the form of " the agglomeration " implies a multiciplicity of urban centres, thus the model radioconcentric of GROER (1936) (3), is rather related to the preindustrial town where the system of transport is developed still little. The town extends then according to the transportation routes: water ways, roads, railways creating of the favorable situations of accessibility and supporting the regrouping of certain activities. Thus in 1947, plan ABERCROMBIE (4) symbolizes the new polycentric model.
After the second world war the " great sets (15) guarantor almost exclusively with the only need for housing, are constuits in periphery of the old cities. These massive extensions of the town were not equipped with the attributes of secondary centrality which they should have received.
The " new cities ", in England, then since 1965 in France, were one of the attempts caused by the State to answer the problem of development of the great agglomerations. (cf. plan of the network of new cities.) Each new town, according to its history, and its choices urbanistic, proposed a form of centrality. Evry with the Agora (7), Cergy Pontoise with the prefecture (6), Saint-Quentin-in-Yveline the Market of Philippe Deslandes (11), gathered activities on a central place, around one or more equipment of reference, connected to a system of public transport. Marne-the-valley is structured on an axis with center-stations (9).
Since, equipment installation of large: airports in periphery of the agglomerations, stations, shopping centres, offices, Stage of France (14), generated new centralities. R. Auzelle could write that " the prestige of the airport of Orly (8) and the interest of its techniques, almost perpetual animation that it causes, the daydream which it gets, all that contributes to attract the population of suburbs ". This airport also inspired Gilbert Becaud in the song " Sunday with Orly ".
The stations benefit today from their function of exchange to develop commercial equipment and services, it is the case of the Station of North in Paris (10)
Conversely, the shopping centres, such that of Valley of Europe with Marne-the-Valley (13), are localised according to a logic of flow, (economic people, vehicles, exchanges...), around trade of great distribution, and see being grafted with them other services and equipment.
Defense (12) constitutes an exception in the peripheral developments. It is the only pole which competes in attractivity with the historical center of Paris for the ancillary activities. One will have needed for that the constant mobilization of the State over several decades.
Lastly, as announces it J.C. Gallety the " centrality " must be based on good functionalities but also on the image, the wellbeing and the visual pleasure. That passes by the quality of architecture, public space and the landscape. The " logic of scene " must become a major concern of the building owners, because there cannot be true centrality without urban art.
V CITE-JARDIN, CENTRE TOWN, PUBLIC PLACE, STATION, GALLERY.