The exterior architecture of the Thomas T. Gaff House is an example of a 17th-century
Châteauesque manor, but only two rooms in the house follow French style. Gaff instructed the designers to include novel conveniences such as a hot-air system to dry clothes, a
trapdoor to his
icehouse so that deliveries could be made directly from the street, and cork insulation for his wine cellar. The interior features a mixture of 17th- and 18th-century designs. The main hall and dining room are lined with wooden paneling,
Elizabethan wainscoting, and a
sideboard that was originally used in an
Italian monastery. The reception hall, which at one time doubled as a living room, contains a wooden stair rail with
baroque scrollwork and walls that are covered with
Louis XIII style oak paneling. The drawing room resembles 18th-century interior design with lighter wood used for paneling and basic geometric lines. In the sitting room, a hidden, movable wooden wall reveals the two-story
Edwardian ballroom, which features a multivaulted wooden ceiling and ornamental plasterwork. The wood that covers the ceiling was discovered during a repair operation. A dome with a stained-glass
cupola is located above the center of the ballroom. This room is used for charity balls, formal dinners, and as a gallery and concert hall. There were originally 220 drawings of the house's design by de Sibour, but only 20 survived. ==References==