The floor plan of the Millikin home is very similar to Millikin's Pennsylvania birthplace. The first floor is bisected by a large central hall and includes two parlors, dining room, library, kitchen, and breakfast room. Ornate fireplaces are found in the first-floor rooms, and plaster reliefs decorate the ceilings.
The main rooms and staircase feature extensive walnut and butternut woodwork. The full-length window shutters are reproductions of the original window treatment.
The north parlor serves the Millikins as their "company parlor." It has been restored to imitate a typical Victorian parlor and is furnished with three pieces for the Millikin collection.
The south parlor was used by the Millikins as their "family parlor." Both parlors have beautifully painted ceiling frescoes, reproductions of the original design, and reproduction floral Administer carpeting typical of the period.
The sheer size of the grand hall makes it impressive. It is 11 feet wide and over 30 feet long. Originally, the staircase was located along the south wall of the hallway, which Mrs. Millikin felt made the hall both cold and dark.
The acid-etched camphor glass doors at the entrance of the dining room depict fruit and fowl. They are original to the home, as is the Eastlake dining room furniture.
The library was a favorite room for the Millikins because it was more intimate than the parlors, and its southwest exposure made it bright and cheery.
An art nouveau stained glass window decorates the bay on the north.
The most dramatic feature of the home is the large central staircase. A stained glass oriel window with a bench to seat ten beneath it is visible on the landing. On the ceiling above is a pink, gray, and blue mural of cherubs on canvas.
During the Millikins' time the second floor consists of seven rooms.
The full-length window shutters of the first floor are repeated in the bedrooms of the second floor. Two of the fireplaces are slate finished to simulate marble.
The northeast bedroom originally had giant hydrangeas painted on the ceiling and was known as the Snowball Room.
The glass in the transom above its entrance is dedicated to the Decatur Art Class, founded in 1880. Mrs. Millikin was one of the founders of the organization, and they often met in her home to study art, culture, and philosophy.
It is speculated that the southeast bedroom served as the master bedroom.