London

Andrea Comas / Reuters

How Many Trees is Enough?

When it comes to reducing pollution, the key isn't the number of trees you plant but where you plant them

Reuters

The Only Hope for Reducing Traffic

A new study makes the fundamental case for congestion pricing

Thermal Cities/Steve Lowe

CAT Scans for Cities

Researchers are using thermal imaging to diagnose energy efficiency in the built environment

Flickr user: "raindog" under a Creative Commons License

Civic Symbolism: A Survey of City Hall Architecture

Which city hall buildings manage to capture something specific about a city's culture?

Payton Chung

Cutting Car Use at the Neighborhood Level

8 European projects show how design and planning can reduce automobile dependence

Flickr user: brunosan, under a Creative Commons license

The World's Best Subway Maps

20 mass transit maps worthy of hanging on your wall

Reuters/Tony Melville

One Downside to Bicycle Commuting: Biker's Lung

London bike commuters found to breathe in more soot than pedestrians

2010 File photo Associated Press/The Philadelphia Inquirer

Are Violent 'Flash Mobs' Really a Trend?

After two summers in a row of disturbing group violence in cities like Chicago and Philadelphia, authorities look at the intersection of technology, poverty, and race

Yuriko Nakao, Reuters

The 25 Most Economically Powerful Cities in the World

Most of the world's capacity for economic growth is centered in its metro areas. Which cities top the list?