Many recent publications associate the sustainable city, nature in cities and the desirable city (French Ministry of Ecology 2011, WWF 2010, Urbanisme 2011). They highlight the need to build a new relationship between cities and nature by ceasing to consider them in opposition to one another. There is doubtless the obligation to meet the needs expressed long ago by citizens who want access to spaces where they can either meet or talk (sandpits, areas for playing boules or board games, picnic areas, etc.), or simply daydream or spend time alone (walking and exercising, resting and meditating). Pierre Sansot has built his work on these spaces, attentive to the diversity of what goes on there. In considering issues such as flood risk (areas where rivers have shifted course), greenhouse-gas emissions (carbon storage), global warming (heat islands and cool areas) or biodiversity (special biotopes), a functional view of nature in the city is now emphasized. At the same time, however, one must not forget that nature in the city, whether natural and wild (landscaping and streams) or cultivated and exploited (parks and gardens) is a powerful vector of (usually positive) emotions. The fact that nature is so often in the foreground of representations of urban projects therefore owes nothing to chance.
Nature to the fore in the desirable city: when nature sells
In this way, the image of a proposed development project is conveyed by artists’ impressions and simulated overviews that express the urban planner’s take on the project. Cleverly designed by experts, these overviews have one crucial goal: to appeal! To appeal to local councillors and panels of judges, if there is a competition, and to appeal to all those involved in city life, directly or otherwise: local citizens, developers and builders, residents and voters, and obviously the future buyers of the properties on offer. It is well known that purchasing behaviour is dictated by the sphere of emotions. Everything therefore has to appeal: the street, the neighbourhood and the city must all be desirable! In reviewing the records of award-winning eco-neighbourhood projects in the call for projects organized by the French Ministry of Ecology,  the overview drawings proposed by all the candidates scrupulously respected what appears to be an unwritten rule: in the foreground, trees and grass and sometimes a pond, and of course happy people, often including a beaming mother with her young children as a bonus; and in the distance, indications of building developments that even professionals cannot fully decipher. By masking the project and its imperfections, vegetation invites the spectator to indulge in a bucolic reverie after the manner of a Watteau painting. Are these deceptions? Perhaps, but is it possible to get away from the rules of advertising when the project itself is launched on the back of brochures and images? Indeed, those who criticize artists’ impressions of urban projects designed like publicity posters are somewhat hypocritical. After all, for most people, the key components of the desirable city are sunshine, greenery and pretty mums! But aren’t we perhaps forgetting that nature in the city can also enhance or erode the value of land and property?
When nature is not enough to make the city desirable: the example of the “grands ensembles” 
The “grands ensembles” (large-scale social housing complexes) emerge today as an archetype of the repulsive city. It is far from alone in this respect: old, run-down neighbourhoods and inner suburban areas undergoing change can also be added to the list. In France, we have lost sight of the fact that the concept of housing complexes was violently opposed to the older one of the garden city. Le Corbusier’s challenge of Ebenezer Howard’s concept was in part an expression of the fierce opposition between progressives and reactionaries, between green spaces and allotment gardens. Thus, for a given density, the “radiant city” is a kind of photographic negative of the garden city: a block of apartment buildings set on its foundations in the middle of a public park, its “haven of greenery”.
This concept was rolled out in many forms as the basis of numerous large-scale social housing projects, in which, it must be emphasized, density remained low – comparable to that of a private housing estate or subdivision – with at least half of the total surface area devoted to open spaces. In all these projects, the buildings were organized around an English-style green space, with lawns, flowerbeds and wooded areas to give the impression that these natural elements were there before the area was urbanized. Green spaces might be broken up into a number of smaller spaces, as at Les Grandes Terres, built by Lods & Honegger at Marly-le-Roi, or take the form of one large space, as in the case of Les Courtillières, built by Aillaud at Pantin (Pouvreau 2011). The “city in nature – nature in the city” approach adopted at Le Lac in Bordeaux, proposed by Arsène-Henry, was even printed in green ink!
But the everyday reality of these neighbourhoods is that green spaces are what is left over once the buildings and roads have been finished: a huge, abandoned, ill-defined area which always costs too much to maintain – often neglected to such an extent that nature has reasserted itself for the benefit of biodiversity. Not surprisingly, these green spaces have never conveyed a positive image of these neighbourhoods. An abundance of greenery is not enough to make the city desirable.
Nature as a decisive feature of the hedonistic approach to the desirable city
In literal terms, the desirable city refers to a hedonistic vision of the urban condition. It is not clear that this philosophy based on immediate individual pleasure-seeking is compatible with that of sustainable development, based on meeting the needs of future generations. But hedonism has become a crucial feature of housing prices, the only one that can explain the differences between neighbourhoods, blocks and buildings, and within the same building, the differences between identical apartments. This is consistent with the age-old estate agents’ golden rule: what matters when choosing a home is location, location, location: (1) the location within the city or urban area; (2) the location within the neighbourhood; and (3) the location within the street, block or building.
In this respect, suburbia, situated between the compact city and the countryside, offers a location that is particularly enviable, thanks to its easy access to employment, amenities (e.g. healthcare, education), services and businesses, and all the more desirable because building land is plentiful and affordable. In this context, preserving a view over a natural site, a nearby park or public garden, a private garden, a tree-lined avenue or even a remarkable feature are objective values. Green spaces are thus considered as urban amenities that must be designed and used to meet the needs of residents and visitors: for strolling and contemplation, for playing games or sports, or as picnic areas or open-air bars. The more care that goes into designing and creating green spaces – and the better they are organized, used and maintained – the greater the effect they have on property prices. Unfortunately, above a certain price level, the desirable city becomes inaccessible to all but the highest social classes. While the desirable city owes everything to its location, the sustainable city should provide a desirable situation for each of its inhabitants.
Coming to terms with nature in the city: an “overriding obligation”
There is no need to reiterate the argument about the “overriding obligation” to accommodate nature in the city: in general, there is a broad consensus, notwithstanding some occasional, local disagreement about whether to urbanize sites that are as yet free of any development or whether to allow a brownfield or military site to return to nature. However, we cannot overemphasize the need for a programmatic approach to the design and operation of spaces dedicated to nature, both on the scale of the urban area – and the catchment areas of the waterways that pass though it – and on that of the neighbourhood or block. This approach must be based on the expectations of residents and visitors, in accordance with their needs and practices. It must be measured against related sector-specific policies: public space (transport infrastructure, parking), housing and urban policy (local urban management, security), economic activities (including leisure and tourism) and health (fitness trails, walking). There would be nothing worse than continuing to adhere to the concept of ornamental green space which, through lack of maintenance and use, turn quickly into abandoned areas that merely exacerbate the degradation of the surrounding urban space and add to the implicit scorn of its residents.
Maps of levels of “well-being” in the Île-de-France (Paris) region by Lise Bourdeau-Lepage and Élisabeth Tovar (2011) show that it is not enough to simply live near a remarkable natural space to ensure long-term well-being among residents. While one can only commend the remarkable work of the staff in charge of the parks in the Seine-Saint-Denis département,  it is here that levels of “ill-being” are highest. For instance, the departmental park at La Courneuve, with its 415 particularly well-maintained hectares of green spaces, does little to improve the image of a town marked by the construction of the “Cité des 4000” estate, whose “dehumanized space” was already a source of anguish in 1961 for Jacques Sgard, the landscape architect involved in the operation. Similarly, in Clichy-sous-Bois, the town’s green spaces (110 hectares of woodland within the departmental forest of Bondy, La Fosse-Maussoin departmental park, Bellevue park, lawns in the town centre and the Dhuys aqueduct green track) do not provide a sense of well-being for local residents, many of whom are consigned to housing estates with green spaces that are as abundant as they are useless. It comes as a surprise to learn that the urban renewal project in this town (ANRU 2009) does not address the subject and focuses primarily on housing and buildings.
To paraphrase Adolf Loos’s famous maxim, it is clear that to consider nature in the city as merely an ornament is immoral, if not criminal. Organizing the city or its neighbourhoods around streams, rivers and lakes, parks and pleasure gardens is not enough to make them desirable. In sum, taking into account how people deal with nature in the city is doubtless the first step of a virtuous approach leading to the creation of value through the sensation – reinforced or restored – of collective and individual well-being. Indeed, is it not the perception of well-being among residents that makes a city so desirable for visitors?