The remarkable "Castle" Federal building in downtown Saginaw had been slated for demolition several times but was saved from destruction in each instance by organized action led by the society. When the building was again slated for demolition in the 1970s, the Historical Society of Saginaw County took action to have the building placed on the National Register of Historical Places. The County Board of Commissioners acquired the site in the 1970s and set aside space for the creation of a museum of Saginaw history. Barrier-free access was added and the closed tower and circular staircase were reopened after 40 years. Supported by a county millage, the Historical Society of Saginaw County has operated the building since 1992.