William K. Vanderbilt House
The William K. Vanderbilt House, also known as the Petit Chateau, was a Châteauesque mansion at 660 Fifth Avenue in Midtown Manhattan, New York City, on the northwest corner of Fifth Avenue and 52nd Street. It was across the street from the Triple Palace of William Henry Vanderbilt, which occupied the entire block between 51st and 52nd Streets on the west side of Fifth Avenue.