Chicago, Illinois

Green grid: As other U.S. cities struggle with aging infrastructure, Chicago is renewing itself with a greener skyline and new building standards. The city's eco-cred has soared with the launch of its Green Roofs campaign, a push to cultivate gardens atop public and private high-rises. The goal: reducing energy consumption and introducing air-cleansing and air-cooling vegetation into one of America's densest urban environments. City Hall already has a green roof (pictured), and Millennium Park is one of the world's largest, situated atop an underground commuter-rail station; in addition, 500 rooftop gardens are sprouting up on buildings throughout the city.

Living city: For an aerial view of the rooftop gardens already in bloom, ride up to the observation deck on 103rd floor of the Willis Tower. On the streets below, visitors can ride more than 50 miles of bike trails, using the city's new bike-sharing program to explore that world-famous lakeshore.

Sustainable stay: Chicago suffers an embarrassment of choices when it comes to green-certified lodgings, but the 483-room downtown Hotel Allegro stands out for its commitment to organic cleaning products and its extensive recycling program.

Hotel Allegro
171 W. Randolph Street
Tel: 312 236 0123

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