William Kissam Vanderbilt (1849–1920) had three houses designed by Richard Morris Hunt. His townhouse, the "Petit Château" at 660 Fifth Avenue, New York, with details drawn in part from the late-Gothic Hôtel de Cluny, Paris, proved an influential example for other Gilded Age mansions, but was demolished in 1926.
Vanderbilt Houses | Fifth Ave, NYC (circa 1901s) looking north from 51st. Brown buildings are residences built for William H. Vanderbilt's family and two of his daughters; the lighter colored building is W. K. Vanderbilt's Petit Chateau and beyond that are the towers of St. Thomas Church and Fifth Ave Presbyterian Church.
Cornelius Vanderbilt II purchased and demolished 3 brownstone houses on the southwest corner of 57th Street and 5th Avenue in preparation for his new mansion. Description from pinterest.com. I searched for this on bing.com/images
William Henry Vanderbilt house 1881- 640 5th Avenue at 51st St. J.B. Snook architect. A portion of the identical mansion can be seen on the right. William Henry had the matching houses built for his married daughters Margaret Shepard and Emily Sloane. They were connected by a one-story vestibule.
The William H. Vanderbilt Family at home (oil on canvas, 1873) pictured in the Vanderbilt house on 40th Street and Fifth Avenue (now part of The New York Public Library). Florence Vanderbilt (later Twombly), then age 19, is fifth from the left, wearing yellow.