Chicago, for example, has about 350 green-roof projects covering more than 4.5 million square feet.

WSJ: How to Build a Greener City

The skylights covering the roof provide interior lighting, as well as additional height inside and out.

BBC: An Alvar Aalto tour of Finland

It had to be preserved, and Foster's scheme for so doing entailed sweeping away the clutter of now obsolete bookstack buildings from around it and covering the court with a light glass-and-steel roof, creating Europe's largest enclosed space, which will function as the access core of the museum.

CNN: ASIANOW - TIME Asia