Entrepreneurship's Greatest Challenge: Rebuild Detroit

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Renaissance Center

Dominating downtown and an imposing symbol of the auto industry's grip, the Ren Cen was financed by Ford but has been GM's headquarters since 1996.

Built: 1973

Square Feet: 5.5 million

Office Occupancy: 95 percent

Long Road: Despite the auto bailout's success, Michigan has regained only a fraction of the 800,000 jobs it shed from 2000 to 2010.