Once awash in vacancies, the downtown Detroit office space market is experiencing a reversal of fortune that is steadily filling old empty buildings and luring corporate tenants out of nearby suburbs.

This shift has already upended some long-standing dynamics of city versus suburban leasing prices and building occupancy rates. For certain companies, an inner-ring suburb like Southfield is now the place to go for a deal on rent.

Fifth Third Bank was the latest big-name company last fall to announce a relocation from a suburb to downtown Detroit, following moves by ad agency Lowe Campbell Ewald from Warren in late 2013, Blue Cross and Blue Shield of Michigan from Southfield in 2011 and recent decisions by accounting and law firms to open (or reopen) Detroit branch offices.