I don't know if this helps, but the Ponce de Leon Hotel, now
Flagler College in St. Augustine, Florida, was one of the first, if not the
first building to be made from reinforced concrete.  Henry Flager was
apparently an innovator in this area, and the hotel is significant enough
to be mentioned in standard architectural histories.  I don't know whether
domestic structures would be significant or not.
 
james cusick
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