The world's top cities for people and planet by National Geographic

Today’s cities are finding it hard to be both livable and economically strong. Not one has truly balanced people, profit, and the planet, according to a new report on an index that ranks cities by sustainability. The index, from global design firm Arcadis and the Centre for Economics and Business Research, ranks cities’ success based on social, environmental, and economic factors.

Arcadis used 32 indicators and a cross section of the world’s urban areas, so not all capitals or large cities are necessarily represented. A city is scored on each of the three sustainability factors; its overall score is the average of those.