The oldest extant house on the street, this five-bay structure was constructed as speculation by John Dixon, the brother of Roger Dixon, who tried to develop the street. In 1772 Dr. Charles Mortimer, Mary Washington's physician, purchased it and later constructed other houses on the street. The Greek Revival portico is a twentieth-century addition; the iron fence dates from c. 1850. The house, with its gardens and outbuildings, retains its original relationship to the Rappahannock River.