https://daytoninmanhattan.blogspot.com/2016/11/the-j-b-francis-herreshoff-house-no-620.html
Daytonian in Manhattan: The J. B. Francis Herreshoff House - 620 West End Avenue
As the 19th century drew to a close, the Realty Improvement Co. laid plans for an unusual project--mirror-image mansions on West End Ave...
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