DETROIT-About 1,700 employees of Rock Holdings Inc., which includes subsidiaries Quicken Loans, Rock Gaming and Fathead, began moving in today into four floors of the 1.1-million-square-foot Compuware building Downtown. The move is heralded as another much-needed success story for the struggling Motor City, with its 30% office vacancy rate, though this move is less than the new office tower that CEO Dan Gilbert had wanted to build in 2007.

Rock will occupy about 244,000 square feet of the 15-story building, taking the ninth through 12th floors. Constructed in 2003 for $350 million, the complex at the center of the Campus Martius district is of the few new office towers built in the past 20 years in Detroit.

Though two new sports stadiums were finished in the past decade downtown, General Motors moved its headquarters to the iconic Renaissance Center and the New Center area has been spruced up, many of even the most popular office buildings have struggled to avert foreclosure and the population has continued to shrink. Even major chain grocery stores have stayed away from the city.

However, a few employees have said they look forward to moving Downtown from their former 210,000-square-foot headquarters building in Livonia. A spokeswoman tells GlobeSt.com that “everyone is excited” to be part of Detroit’s rebirth. Bruce Schwartz, president of Rock subsidiary In-House Realty, said his group is also working to place employees into homes in the city. The group hosted a company bus tour which showcased condos and apartments available in areas such as Midtown, Brush Park and the East Riverfront area.

Rock is leasing the four floors for five years, in an area where the average rate is about $23.77 per square foot for class A space, according to a Grubb & Ellis Q2 market report. The spokeswoman says the company is considering more space downtown. “We’ve been on a lot of building tours,” she says. She did not return questions about what is happening with the company’s now-vacant building in the suburbs.

Dan Gilbert, founder and chairman of Quicken Loans and principal of Rock Gaming, is behind a $1 billion venture to bring casinos to Cleveland and Cincinnati.  Gilbert is also majority owner of the Cleveland Cavaliers basketball team.