Bursting at the seams isn't better

Think of huge, thriving megacities such as Tokyo, Los Angeles, and Buenos Aires. Then think of where you would most like to live. Probably not Tokyo, LA, or Buenos Aires – even if geography weren't a factor.

It turns out that none of the top 10 most populous cities appears on the top 10 quality-of-life list. The latter are more modest places such as Vancouver, Vienna, and Copenhagen, according to the Economist.

Take London, for example – that tourist favorite with cheap theater, tea and crumpets, and ridiculous amounts of history. Very fun for a two-week trip. Not so fun sometimes, if you live there.

At a recent Harvard symposium, Dame Judith Mayhew, chairman of Policy and Resources of the Corporation of London, spoke of that darker side: 29 percent of households live below the poverty line; 43 percent of children live in poverty. And the strains of rich and poor residing side by side emerge in higher crime, sky-high housing costs, and crumbling education.

But there is a plan, the London Plan, masterminded by the mayor. Ken Livingston's idea is to move the city's center of gravity east to the abandoned docklands, one of the last areas open to development. There, he hopes, new jobs and housing will ease the growing congestion of 100,000 more people adding their weight to the city's human mass each year.

Whether or not Livingston manages to shift centuries of tradition, the unsteady lurches in big-city growth can stretch the seams to the limit. There's rarely a bust, just a gradual sinking of living standards.

Yet the world still gravitates to the city. More than half the global population will be in town within five years, the UN predicts. This adds urgency as city planners race to stretch the urban fabric.