 The Old Stone House (3051 M Street NW) was built in 1765 by Christopher and Rachel Layman.The house was sold in 1767 to a wealthy widow, Cassandra Chew, who constructed a kitchen in the rear in 1767, and a second floor between 1767 and 1775, and a third floor in the 1790s.It remained in private hands for almost two centuries, used as a home and place of business, until the federal government purchased it in 1953 .