From one of our favorite blogs, Daytonian in Manhattan, a post from a couple years ago:
The Long-Forgotten "Campbell Apartment" - Grand Central Terminal
John Williams Campbell was, as his wife once said, “a showman.” He liked things big and splashy. Like his office.
Born in Brooklyn, Campbell never attended college. Instead, in 1898 at the age of 18, he entered his father’s firm, the Credit Clearing House. Little by little he worked his way up until by the 1920s he was president of the company and was appointed to the board of the New York Central Railroad.
Through the railroad appointment, he rubbed elbows with William K. Vanderbilt II whose office was in Grand Central Terminal. Most likely through this friendship Campbell first saw the vacant office space at the southwest corner of the terminal.
The immense office, then the largest ground floor space in the city, was 3500 square feet -- 60 feet long by 30 feet wide -- its walls rising 25 feet to the ceiling. It was the sort of office that would impress.
Campbell signed the lease in 1923 and commissioned Augustus N. Allen to transform it. When Allen was done, Campbell had a Florentine palazzo fit for a doge. A mixture of complimentary styles – Romanesque, Renaissance and medieval – the space made the intended impact.
Anchoring one end was a huge stone baronial fireplace (which hid a steel safe). Leaded glass windows admitted light and the wooden ceiling beams were hand painted in brilliant colors. There was a mahogany musician’s gallery with carved quatrefoil designs, a pipe organ, a baby grand piano, 19th Century Italian furniture (pretending to be 13th Century), and Campbell’s overpowering desk.
More impressive than the $1 million art collection lining the walls was the custom woven Persian rug that covered the entire area. The carpet cost Campbell $300,000 in 1924 – an amount that would translate to between $3 and $4 million today....MOREAnother big NYC office that may be of interest was Jay Gould's Erie Railroad office in the Grand Opera House:
Daytonian posted on this one as well:
From Silk Purse to Sow's Ear -- 23rd Street and 8th Avenue