The McElroy Octagon House, also known as the Colonial Dames Octagon House, is an historic octagonal house now located at 2645 Gough Street at Union Street in the Cow Hollow neighborhood of San Francisco, California. William C. McElroy built it in 1861 across the street from its present location. It was vacant and neglected in 1951 when The National Society of the Colonial Dames of America in California bought it, moved it across the street and began its restoration. In 1971 it became San Francisco Landmark 17. It, the Feusier Octagon House and the Marine Exchange Lookout Station at Land's End are the only three remaining octagon houses in the city.
On February 23, 1972, it was added to the National Register of Historic Places.
The house is open to the public for tours.
The NSCDA-CA website at http://octagonhouseca.org or http://nscda-ca.org/octagon-house/
List of San Francisco Designated Landmarks
Octagon House, 1861 - The National Society of the Colonial Dames of America