Entrepreneurship's Greatest Challenge: Rebuild Detroit
Dan Gilbert's $12 million building renovation. The location was once home to a glorious theater that was razed for a parking lot. The building reopened last year.
Square feet: 50,000
Number of Ventures: More than 30
Welcome Back: One venture in the space is Chalkfly, co-founded by two brothers who ditched gigs in D.C. and Chicago to return home to Detroit. "The entrepreneurial renaissance over here brought us back," says co-founder Andrew Landau, 27.