 Upon the building's completion, the basement, ground floor, and mezzanine housed the banking offices, and there was a "richly decorated" board room on the mezzanine, as per the company's requirements.The two-story banking room included a barrel-vaulted ceiling and was split into two floors by 1919.When Lehman Brothers occupied 1 William Street, it maintained a fancy private dining facility for its employees in the building.