Work resumed on what will be one of the tallest towers in the Boston skyline following several months in which the Winthrop Center’s future hung in the balance. The relaunch by the local contractor Suffolk comes after Millennium Partners Boston, developer of the planned 52-story downtown office and apartment building, secured a $775-million construction loan.

Crews back on site recently installed superstructure columns following the financing deal. The 65-ft-tall columns are designed to support a grand public hall for the lobby and part of the tower complex, according to a project spokesperson.