For nearly 25 years, the Madison Theater, a dingy, worn-out theater on a quiet stretch of Detroit's inner city, stood vacant.
But in 2011, Dan Gilbert, the billionaire founder of Quicken Loans, purchased this 1917 building, and created an all-out Mecca for start-ups.
It opened last year, and now houses more than a dozen start-ups. The "industrial chic" building also includes a 135-seat auditorium, and a giant rooftop patio.
