Octagonal homes were a mid 19th century architectural fad, but few survive intact today. This one, which is a now a museum over near Cow Hollow, remains, and is open to the public on selected days.
I was delighted to be in San Francisco on one of the museum's opening days. The house has a long history (it's one of only three such structures remaining in San Francisco) before it was acquired and restored by the Colonial Dames.
The dames serve as volunteer docents and tell the story of the house and how it came to be in its present location. Inside, there are splendid displays of Colonial era furnishings and artifacts.
The original circular stairwell is no more, but a beautiful carved curved staircase still exists, as does a n unusual ceiling design (be sure to look up!)
Admission is free, with a suggested donation of $5. Worth a visit if you love history, architecture, or both!