This is a terrific vintage picture from ‘San Francisco: As it Is / As it Was by Paul Johnson and Richard Reinhardt. At the left is the doorway to A. N. Towne’s mansion destroyed in the 1906 Earthquake. The doorway is now the Portals of the Past site in Golden Gate Park. Two of today’s survivors from the disaster are the James Flood Mansion, now the Pacific Union Club, on the left, and the Fairmont Hotel at right. The link below will allow you to see all of the posts for this series of pictures on Nob Hill.