Jaime Lerner is an architect and urban planner. Former president of the UIA-International Union of Architects and three-time mayor of Curitiba, Brazil, Mr. Lerner has twice served as governor of Parana State. In 2010 was nominated among the 25 most influential thinkers in the world by the Time magazine.

From Harvard Bussiness Review 10:21 AM Monday April 18, 2011 
Published in partnership with the Advanced Leadership Initiative at Harvard University.

How can cities be more vibrant, more vivacious? How can cities be "revitalized"? First and foremost, what brings life to a city is its people — and the better the quality of life of the city, the better it will be for its citizens and the more livable and lively it will be.

Many cities are losing the battle against degradation and violence because they settled for the view that difficulties were too big and could only be dealt with after all planning instruments and financial resources were in place.

I see cities not as problems, but as solutions. I would argue that any city, willingly, can be transformed for better in a relatively short period of time, provided that we embrace a more generous approach to them.

This perspective misses the fundamental understanding that the city is a collective dream. To build this dream is vital. Without it, there will not be the essential involvement of its inhabitants. It is crucial to project successful scenarios that can be desired by the majority of the population, to the point that they commit to it. Building this vision of the future is a process that acknowledges, welcomes and embraces the multiple visions that managers and inhabitants, planners, politicians, businesses, and civil society have of their city and sets up co-responsibility equations to make it happen.

The more generous this vision and the sounder the equations, the more good practices will multiply and, in a domino effect, the more rapidly they will constitute a gain in quality of life and solidarity.

Strategic punctual interventions can create a new energy and help the desired scenario to be consolidated. This is "Urban Acupuncture": it revitalizes a "sick" or "worn out" area and its surroundings through a simple touch of a key point. Just as in the medical approach, this intervention will trigger positive chain-reactions, helping to cure and enhance the whole system.

There are three fundamental issues that are key to the good quality of urban life: sustainability, mobility and sociodiversity.

As far as sustainability, observe some key tenets. Use your car less, especially for routine itineraries. Separate organic from recyclable garbage at home. Live closer to your work. It's important to have more sustainable, more energy efficient materials used in construction. But it will be of little use to move from one "green building" to the next if the layout of the city itself is not sustainable.

In terms of mobility, give priority to public transport and use all modes available in the best and most efficient way possible. I also believe that "private" vehicles without private ownership, for example, the Velib in Paris, will increasingly play a larger role in urban commutes.

Sociodiversity encompasses the need to embrace and celebrate the multiplicity of peoples with different income levels, ages, religions, races and so on within the city, while at the same time preserving the traits that define each one's identity. This is what will ensure social cohesion, urban safety, and ultimately the possibility of encounters within the city and the willingness to congregate in its communal spaces.

To make this happen you need creativity. If you want creativity, cut a zero off your budget. If you want sustainability, cut off two. If you want solidarity, make your identity count while respecting diversity.

These concepts come together in the metaphor of the Turtle embodying life, work and movement — if you break down the shell of the turtle, it will die. So, the "vital" city is one that, as the metaphor emphasizes, provides a protective shell for integrating compatible urban functions and effecting change without breaking down the life-sustaining shelter.