Mabel Grosvenor's Home at 2203 Wyoming Avenue, NW
The Colonial Revival-style house at 2203 Wyoming Avenue that is currently on the market (as of this posting) was designed by the architectural firm of A. B. Mullett & Co. in 1912. It was not designed by the noted architect Alfred B. Mullett as it has been advertised by realtors. When the house was designed, Alfred Mullett had been dead for 12 years.

2203 Wyoming Avenue, NW. Author's photo.
True, the name of Mullett is associated with the house, but it was the architectural firm managed by two of Alfred Mullett’s sons that must be given the credit for the design of the house. While wanting to associate the house with Alfred Mullet may seem like a selling point, perhaps there is something more historically intriguing about the house than the Mulletts.
In 1882, Alfred Mullett set up a practice in New York City with architects Hugo Kafka and William G. Steinmetz. Later, he established his own firm, Alfred B. Mullett & Sons, in order to practice with his two elder sons, Thomas and Frederick. In 1889, Alfred’s sons, as well as a draftsman for the firm, James F. Denson, were made partners and the name of the firm was changed to A.B. Mullett & Co.
The firm continued after Alfred Mullett's suicide in 1890, doing general work in the Washington, D.C. area. After Frederick Mullett's death in 1924, Thomas Mullett brought architect Russell O. Kluge into the firm. Kluge inherited the business after Thomas Mullett's death in 1935. A. B. Mullett & Co. ceased operation permanently when Kluge was drafted in the Second World War.
The house at 2203 Wyoming was built by the Mulletts for George W. Moss, a Washington travel agent whose business “Moss Ticket Agency” was located in the old Ebbitt House. Moss also served as the local representative of the Cunard Steamship Line. After Moss died, his widow, Gertrude Blanchard Moss, remained in the house until her death in 1931. The year she died, she had added a two-story brick addition onto the house. In her will, Gertrude left her brother, Arthur Moss, an attaché of the District Supreme Court, the use of the house until his death, at which point it was to be sold and the proceeds distributed among remaining family members and charities.
The house was then purchased by Dr. John Bachman Hyde in the early 1930s. During Hyde’s tenure, the house was briefly occupied by Rev. Dr. Oliver J. Hart, rector of St. John’s Episcopal Church on Lafayette Square, at which time it became the temporary rectory for the church.
Perhaps the most noteworthy owner of 2203 Wyoming Avenue was Dr. Mabel Harlakenden Grosvenor, Mabel was the daughter of Dr. Gilbert H. Grosvenor and the granddaughter of Alexander Graham Bell. Mabel was born on July 28, 1905 in Baddeck, Nova Scotia, the daughter of Elsie Bell Grosvenor, the inventor's eldest child, and Gilbert Hovey Grosvenor, the first president and longtime editor of National Geographic magazine. She was named for her grandmother Mabel Gardiner Bell, who had lost her hearing after a bout of scarlet fever. Mabel spent her early childhood days in the Grosvenor’s home just across the backyard from her grandfather Alexander Graham Bell at 1328 Eighteenth Street and helped out as the aging Bell’s secretary.

Alexander Graham Bell with three granddaughters, Mabel Grosvenor (right)
Mabel was one of seven women in the graduating class of 1931 of Johns Hopkins Medical School. She practiced pediatric medicine in Washington for 35 years and continued to live in the city at her Wyoming Avenue home after her retirement in 1966. She was also responsible for running her grandfather’s Nova Scotia estate and museum, Beinn Bhreagh.

Mabel Grosvenor with her namesake grandmother, Mabel Bell.
Mabel's neighbors on Wyoming Avenue recall that the house was almost always dark or nearly dark. For a few years before she died, a gentleman would come to chauffeur her and neighbors would sometimes glimpse a small, bent bundle entering or leaving the house.

Mabel Grosvenor's graduation photo from Johns Hopkins University in 1931.
Grosvenor family.
In 2005, Mabel sold the house at 2203 Wyoming Avenue. She died the following year at the age of 101 from respiratory failure at the family's home in Baddeck, Nova Scotia. She was the last surviving individual to have personally known and worked with Alexander Graham Bell.