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| c. 2017 | 
3,415 square foot flat front duplex Italianate built in 1877. Last sold for $20K in 1988. Current estimates value the property at about $4.5 million.  
There was a horizontal addition in 1988. 
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| San Francisco Architectural Survey c. 1975 | 
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| c. 1975 sans garage | 
✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤✤And as a side note...
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| Zuckerburg's garage keystone | 
I took a couple of shots of the house that Facebook built otherwise known as Chateau Chan-Zuckerberg which is just down the street at 3660 21st St. The manse sits sideways on a heavily-gated and alarmed lot so it was impossible to get any full frontals.
Zuckerberg paid $3 million for the property in 2012. The original 1,400 square foot structure, built in 1923, was demolished to make way for a 5,500+ square foot faux Tudor Revival. 
The construction site was heavily guarded and the building process was overly long. In other words a protracted pain in the ass for the surrounding residents.  
I was not invited over for cocktails nor do I expect an invite so no interior shots....Sorry❤︎
Mark Zuckerberg Keeps Pissing Off His Neighbors (BuzzFeed)
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| 3660 21st St street side view | 
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| 3660 21st St street side view above garage  |