In Harlem, a neighborhood network of sensors — and citizen scientists — are measuring a little-understood risk.

Beneath the city, an ingenious, sustainable system uses the Seine to cool down buildings like the Louvre.

While other cities wait for their newly planted trees to grow, the Israeli city is updating an age-old cooling method for the 21st century.

For the first time, two US cities are treating extreme heat as a crisis — and dealing with it accordingly.

With strategically placed channels for air flow, the birthplace of the automobile is using urban design to lower the temperature.

A one-week series about surprising ways cities can crank down the temperature.