The Benjamin N. Duke House, also the Duke–Semans Mansion and the Benjamin N. and Sarah Duke House, is a mansion at 1009 Fifth Avenue, at the southeast corner with 82nd Street, on the Upper East Side of Manhattan in New York City. It was built between 1899 and 1901 and was designed by the firm of Welch, Smith & Provot. The house, along with three other mansions on the same block, was built speculatively by developers William W. Hall and Thomas M. Hall. The Benjamin N. Duke House is one of a few remaining private mansions along Fifth Avenue. It is a New York City designated landmark and is listed on the National Register of Historic Places.

The James B. Duke House is a mansion at 1 East 78th Street, on the northeast corner of Fifth Avenue, on the Upper East Side of Manhattan in New York City. The building was designed by Horace Trumbauer, who drew heavily upon the design of Château Labottière in Bordeaux. Constructed between 1909 and 1912 as a private residence for businessman James Buchanan Duke and his family, the building has housed the New York University (NYU)'s Institute of Fine Arts since 1959.