Dimensions: 28' - 2" x 25' - 3";
Color: Walls are Mars yellow in distemper paint with calcium carbonate added. Floor: oil-based green paint.
Source: Courtyard of the Temple of Nerva Trajan as depicted in plate 15, Book 4 from Giacomo Leoni edition of The Four Books of The Architecture by A. Palladio
Although quite beautiful with its large circular windows and oculus skylight, the function of the Dome Room is not completely understood. The only known long-term occupants were Jefferson's grandson Thomas Jefferson Randolph and his bride, Jane Hollins Nicholas, who lived in the room for a number of months starting in 1815. By Jefferson's death, if not before, the room had become primarily a storage area.
Primary Source References
1807 April 18. (Jefferson to Richard Barry). "As the most important work you have to do here is to finish the floor of the hall and to paint the floor of the Dome room exactly in the same way." 
1809 August. (Margaret Bayard Smith). "We looked into a beautiful and circular room in the dome--it is 26 or 27 feet diameter--has eight circular windows and a handsome sky-light. It was designed for a lady's drawing-room when built, but soon found, on account of its situation in the dome, to be too inconvenient for that use, and was abandoned to miscellaneous purposes." 
1809 August. (Margaret Bayard Smith). "He [Jefferson] afterwards took us to the drawing room, 26 or 7 feet diameter, in the dome. It is a noble and beautiful apartment, with eight circular windows and a sky-light. It was not furnished and being in the attic story is not used, which I thought a great pit as it might be made the most beautiful room in the house." 
1819 July 18. (Cornelia Jefferson Randolph to Virginia Jefferson Randolph Trist). "I will not ask you to make a great search for it [part of a pencil] and think it is in the dome if some of the young gentlemen have nor recognized it as their own, and taken it." 
1819 July 28. (Cornelia Jefferson Randolph to Virginia Jefferson Randolph Trist). "I made apologies to you about giving you so many commissions because I knew you sometimes would sooner die than drag yourself up into the dome where you would have to go to execute most of my commissions." 
1823 June 5. (Virginia Jefferson Randolph Trist to Nicholas Philip Trist). "I have never told you of the nice little cuddy that has become my haunt, and from which I am now writing. Do you recollect the place over the parlour's Portico into which the dome room opened? Since the columns to the portico have been completed, Grand-Papa has had the great work bench removed from it, and a floor layed. Corneilia's ingenuity in conjunction with mine formed steps from the dome into this little closet with a pile of boxes, and having furnished this apartment with a sopha to lounge upon, though alas! without cushions, a high and low chair and two small tables, one for my writing desk, the other for my books; and breathing through a broken pane of glass and some wide cracks in the floor; I have taken possession with the dirt daubers, wasps and humble bees; and do not intend to give it up to any thing but the formible rats which have not yet found out this fairy palace." 
3. Hunt, Gaillard S., ed. The First Forty Years of Washington Society: Portrayed by the Family Letters of Mrs. Samuel Harrison Smith (Margaret Bayard) from the Collection of her Grandson, J. Henley Smith. New York: Scribner, 1906, 71.
5. Nicholas Philip Trist Papers. University of North Carolina
7. Papers of Nichols P. Trist. Library of Congress
- Thomas Jefferson Foundation, Inc. "Restoration of Monticello's Dome Room." (Podcast)