Video from GOOD - Most of the world's population now lives in cities. How can we make sure these urban centers are good homes for humanity? Cities from Bogotá and Rio de Janeiro to Seoul are leading the way, using fresh ideas to reduce pollution and waste; provide efficient, clean transportation; and support biodiversity.

Studies have shown city dwellers have smaller carbon footprints than their countries' national averages

This is Dharavi, Mumbai's largest slum, and it's about to change forever. Once a mangrove swamp on the edge of Mumbai, more than one million people now live in these five-hundred-and-fifty acres. ...

From Florida to China, showcase "green" communities are popping up all over the globe. But some have already failed. Here are four model cities that might actually make it.

World Environment Day was established by the UN in 1972 to give a human face to environmental issues. But as these images show, developing countries suffer the worst effects of waste and pollution. Here, a trash-covered creek in Manila, Philippines, where slums often adjoin rubbish dumps. The country's poorest sift through the garbage to find discarded objects they can sell on or re-use, or even scraps of food to eat

Oxford Circus, in London's West End shopping district, accommodates 43,000 people and 2,000 vehicles every hour. But not very well. It's chaotic, crowded, and dangerous. Here's an animation explaining the problems and solutions

VAUBAN, Germany - Residents of this upscale community are suburban pioneers, going where few soccer moms or commuting executives have ever gone before: they have given up their cars. Street parking, driveways and home garages are generally forbidden in this experimental new district

Trace the past and future expansion of the world's biggest cities with the BBCs interactive map (urbanisation and urban growth) The world in 2050: leading experts give their forecasts for the urban future Making cities work: Detroit, Mexico City, Moscow and China Rural to urban migrants speak out.