05/18/2010 05:12 am ET Updated May 25, 2011

Willis Tower Owner Sued Over Derailed 'Greening' Project

A lawsuit against a co-owner of Willis Tower raises questions about whether it will follow through on a $350 million project to reduce the building's energy use.

A spokesman for American Landmark said the "greening" of Willis Tower is still being planned. "We continue to pursue private and public options for funding and are confident we can achieve our goals," the spokesman said. He declined to comment on the lawsuit.

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