It’s the world’s most visited city, a tourist dream of grand, historical buildings and cobbled charm. But Paris’s secret shame has always been the horror lurking behind its peripherique ring road – the moat that protects the city’s 2 million people from at least 6 million others who live outside in high-rise, ethnic ghettoes or suburban sprawl, choked by dismal public transport and shabby green space.

Now Nicolas Sarkozy wants to answer the critics who call him a cultural philistine by plunging into his new love for architecture and creating a Greater Paris that would be world’s most environmentally friendly and boldly designed metropolis.

When the president invited 10 of the world’s most renowned architects to the Elysée last year and lauded architecture as art that the citizen “does not need a ticket for”, Paris sat waiting for him to announce his own grand building project, along the lines of François Mitterrand’s glass pyramid in the Louvre.

Today as architects including London-based Richard Rogers, as well as French prizewinners Jean Nouvel and Christian de Portzamparc, present their various strategies for Grand Paris, it is clear that the president is aiming higher than Mitterrand’s isolated architectural gems.

He wants to style himself as patron of the most ambitious urban overhaul since Baron Haussmann dramatically changed the face of Paris in the mid-19th century when he carved out wide boulevards and the Champs Elysée.

But the Greater Paris project to reunite Paris’s centre with its neglected outskirts is steeped in controversy as local and national politicians fight over its boundaries, budget, population and new identity before the architectural debate has begun.

In an exclusive preview of their strategy, Richard Rogers’s group told the Guardian yesterday that the biggest challenge was Paris’s “enormous disparity” and the “staggering psychological barrier” between the core of the city and the world beyond the ring-road.

“I don’t know any other big city where the heart is so detached from its arm and legs,” Rogers said at the start of the project.

His team of architects, who have worked with the London School of Economics and French sociologists, will today propose a bold plan to unite Paris’s disparate communities, beginning by covering over the railway lines that “carve up” the city and creating a vast network of lush parks above the tracks.

Mike Davies, director of the project, said: “The train lines going into Gare du Nord and Gare de l’Est are currently canyons of void.” He proposed creating “a continuous green space, a green network” miles long that would link the centre of Paris to its deprived north-eastern outskirts. Underneath it, a separate, hidden layer would contain the mechanics of renewable technologies aimed at launching Paris into a low carbon future.

The Rogers proposals also call for state intervention to completely overhaul areas such as Clichy-sous-Bois, which exploded in urban riots in 2005. Davies described the high-rises as “separate blocks in space”, plonked down in isolation with no identity, city fabric, or village life around them.

“The great unwritten and unsaid is that residents tend to be similar ethnic origin. It’s not a mixed system,” he said. “Monoculture is one of Paris’s biggest problems.”

The plans seek to bring in new, mixed populations to the poor high-rises and the business district La Defence, extend high-speed train lines, create a new metropolitan transport system and cut the myriad layers of local government.

Rogers, who changed the face of Paris in the 1970s when he co-designed the Pompidou centre, will present one of 10 competing strategies that go on show to the public next month. But the question remains whether Sarkozy will act on the various proposals and launch Paris’s biggest overhaul in centuries. “It has to be at the highest level of modern design,” Davies said. “Ordinariness won’t draw people there.”

Other ideas to be unveiled today include the architect Roland Castro’s plan to build a New York-style central park on Paris’s infamous drab housing projects of La Courneuve, and Christian de Portzamparc’s concept for a high-speed elevated train that would run along the ring road.

Today, French president Nicolas Sarkozy will receive the ten architects selected to create Le Grand Paris. Richard Rogers is one of them. Earlier this week, they each gave a 30-minute presentation of their visions (see it here). The task is herculean, the mission quasi-impossible, but the challenge absolutely irresistible for any ambitious architect.

For he or she knows that, as Paul Goldberger writes in the New York Times, “politics and architecture have always been inseparable in this city”. And that “Parisians, with their long and deep commitment to the idea that the city is in the most profound sense a public place, feel that Paris is very much their own possession.”

The most visited city in the world, here is a capital whose great talent has been to interweave the grandeur of its official buildings with the everyday charm of its many quartiers. Or as ex-Parisian and writer Adam Gopnik puts it in his book Paris to the Moon: “Paris marries both the voluptuous and the restricted. It is not the yeses but the noes of Paris, not the licences it offers love but the prohibitions it puts in its way that make it powerful. “

The challenge however is not to reshape Paris, but rather to extend its inherent beauty to its outskirts, les banlieues – a web of small villages, some terribly grand and chic (Neuilly, Versailles, Saint Mandé, Vincennes, Saint Germain-en-Laye), others modest and provincial-looking (Montreuil, Pantin, Malakoff, Montrouge, Saint Gervais) and others still, socially ravaged and architecturally dehumanised (La Courneuve, Clichy-sous-bois). And also to link them. But how do you bring together so many different styles and the city’s “enormous disparity”, as Richard Rogers calls it, into one Grand Paris – especially when the city is so clearly defined geographically by its gates, shadows of former fortifications, and now le périphérique, the circular road encasing Paris? The simple answer is: by being bold. But also by understanding the fabric of French society and its psyche.

The different sketches and 3D renditions of the ten projects make audacious and compelling viewing (see them here). Antoine Grumbach proposes to build the Greater Paris along the Seine right up to the harbour of Le Havre. He may have taken inspiration from Napoleon who once said: “Paris-Rouen-Le Havre: one single city with the Seine as its main road.” Water is also an idea the Italians Bernardo Secchi and Paola Vigano have developed: their Paris is laid out as a “sponge” in which waterways are the new motorways. Christophe de Portzamparc proposes to build four “archipelagoes” and create the biggest European rail station in the north suburb of Aubervilliers. Yves Lion offers the vision of a Paris engulfed in forests and fields where every citizen would cultivate their own vegetable patch. Richard Rogers offers to cover up railway lines that dissect the city by placing huge green spaces and networks above them. In the most brutalist, Le Corbusier-esque project, the Dutch practice MVRDV imagines a tower-block in place of the Sorbonne and motorways cutting through the heart of Paris.

As a Parisian born and bred, I thought the most convincing presentation came from Parisian architect and sometime presidential candidate Roland Castro. He seems the only one to really understand the Parisian mentality, the importance of architecture and politics, grandeur and charm, poetry and citizenship. He not only suggests moving the Elysée Palace to the tough north-eastern suburbs, but also proposes to create new cultural landmarks and governmental buildings, together with a New York-style Central Park on the grim housing project of La Courneuve. The idea is to inject grandeur (as conveyed by the cultural and official institutions) and if possible, beauty, to Paris’s many environs.