647 Fifth Avenue, originally known as the George W. Vanderbilt Residence, is a commercial building in the Midtown Manhattan neighborhood of New York City. It is along the east side of Fifth Avenue between 51st Street and 52nd Street. The building was designed by Hunt & Hunt as one of the "Marble Twins", a pair of houses at 645 and 647 Fifth Avenue. The houses were constructed between 1902 and 1905 as Vanderbilt family residences. Number 645 was occupied by William B. Osgood Field, while number 647 was owned by George W. Vanderbilt and rented to Robert Wilson Goelet; both were part of the Vanderbilt family by marriage.

660 Fifth Avenue is a 41-story office building on the west side of Fifth Avenue between 52nd and 53rd Streets in the Midtown Manhattan neighborhood of New York City. The office tower was designed by Carson & Lundin and built for its developer Tishman Realty and Construction from 1955 to 1957.