On April 25th, 2006, we said goodbye to a remarkable woman, one who had a huge influence on her century. In her 89 years Jane Jacobs completely changed the way we think about cities, their growth and development. Lacking a college degree or any training in urban planning, she was met with scorn from the heavily male-dominated field of urban planning, yet she revolutionized our approach to the subject, substituting spontaneity and organic growth for the top-down urban planning that sought to regulate and constrain the lives of city residents.

She opposed the "urban renewal" policies that destroyed communities. She opposed visionaries like Le Corbusier, who intended architecture to make people live as 'enlightened' people thought they should, and urban planners, like the megalomaniac Robert Moses, who destroyed large parts of New York in the name of modernism. She published "The Death and Life of Great American Cities" in 1961, advocating the abolition of zoning laws and restoration of free markets in land, which she claimed would result in dense, mixed-use neighborhoods that served the wants and needs of people, rather than the abstract dreams of the planners.

She ran an ultimately successful grassroots campaign in New York against the plan by Robert Moses to build a Lower Manhattan Expressway that would have transformed Greenwich Village beyond recognition, passing through the vibrant neighbourhoods of SoHo and Little Italy. What he called "slum clearance" she regarded as vandalism.

In her 1969 book, "The Economy of Cities," she reversed the popular notion that cities were made possible when humans turned from hunter-gatherers to agriculture. No, she said, it was the other way round. Concentrations of people living in proximity in places conducive to trade, specializing and trading with each other and with outsiders, created a demand that led to the development of agriculture in their vicinity.

Her vision of vibrant societies where people interacted with each other and produced between them communities that were not planned from above and outside, but arose naturally and spontaneously, is very much in line with the skepticism of planners and planning that libertarians and neoliberals exhibit. Such communities were certainly the product of human action, but not of human design.

Jane Jacobs died 13 years ago, but her contribution and her legacy have made the cities that have heeded her advice happier places for people to live in.