Thornhill is listed on The National Register of Historic Places. From the National Register website: “The National Register of Historic Places is the official list of the Nation’s historic places worthy of preservation. Authorized by the National Historic Preservation Act of 1966, the National Park Service’s National Register of Historic Places is part of a national program to coordinate and support public and private efforts to identify, evaluate, and protect America’s historic and archaeological resources”.
You may access text and photos by going to the National Park Service website by clicking on this link:
NATIONAL REGISTER OF HISTORIC PLACES – THORNHILL
or by accessing the PDF file directly by clicking on this link –