Thornhill is included in the Historic American Buildings Survey.
From the National Park Service’s Heritage Documentation website: “The Historic American Buildings Survey (HABS) is the nation’s first federal preservation program, begun in 1933 to document America’s architectural heritage.“.
You may access text and photos by going to the Library of Congress website by clicking on this link:
HISTORIC AMERICAN BUILDINGS SURVEY – THORNHILL
or by accessing the PDF file directly by clicking on this link –