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This museum is located in the Octagon House, an 18th century building designed by William Thornton, the first architect of the US Capitol. The home now serves as the oldest museum in the country dedicated to architecture and design. It is operated by the Architects Foundation, a branch of the American Institute of Architects. This is one of the oldest remaining buildings in the city and its presence influenced the organization of nearby structures, thereby playing a key role in the layout of northwest Washington. The Octagon House was added to the List of National Historic Landmarks in Washington, D.C. in December, 1960, and six years later was listed on the U.S. National Register of Historic Places.

  • The Octagon Building in 1936 (
  • Urn-shaped stoves found inside the building (
  • The so-called Treaty Room in 1936 (
The building was commissioned by John Tayloe III and designed by William Thornton. Tayloe was born in Richmond County, Virginia, and went to school amongst the British gentry in Eton and Oxford, England. He became one of the largest plantation owners in the USA, and was considered by many to have been the "wealthiest man of his day." Tayloe was a personal friend of George Washington, serving under him as Captain of Dragoons. He was also an active Federalist, and served as a Delegate in the Virginia House of Delegates and as the Senator of Virginia.

In 1799 he commissioned Dr. William Thornton to build him a winter home in Washington, D.C., to serve as his winter residence. The building was completed in 1800, located at the intersection of 18th Street and New York Avenue, between the Potomac river and the President's residence. The three story building is built of red brick with Aquia Creek sandstone used for the window sills and decorative panels. Other notable features include the exterior ionic columnns, the interior Corinthian columnns, the urn-shaped cast-iron stoves, and the lavishly decorated "Treaty Room" on the second floor. In 1840 the original flat roof was replaced with the hipped roof seen today. The interior has a restrained yet sophisticated Classical style. Upon closer inspection the visitor will notice that the building is not, in fact, an octagon but an irregular hexagon. 

John Tayhoe passed away in 1828, and his wife, Ann Ogle, assumed control of the house. She lived there until her own death in 1855, after which it remained under occupancy of the Tayhoe family for a further fifty years. The building then became a school for girls, and subsequently served as the Navy Hydrographic Office. The American Institute of Architects  purchased the building in 1902, at which point it had become derelict and in need of repair. After a period of restoration it became the headquarters of the AIA. In 1968 the AIA transferred ownership of the building to the American Architectural Foundation, who turned it into a museum two years later.