Cornelius Vanderbilt II Mansion, New York City. Water Color Room. The Vanderbilts bought the entire row of houses behind them and brought in George B. Post and Richard Morris Hunt to build them a palace that would occupy the entire block. When it was completed , the chateau would be the largest home ever built in New York City, with 137 rooms, 37 bedrooms, 16 baths, a library, numerous salons, a baronial dining room, smoking room and a magnificent ballroom.