From the record
“The Huff Archeological Site is a prehistoric Mandan village in North Dakota dated around 1450 AD. The site has been designated a National Historic Landmark, and is one of the best preserved sites of the period.”
Wikipedia article Huff Archeological Site, CC BY-SA 4.0.
One of 11 National Register listings published here for Morton County · listed in 1980 · category: Site · a National Historic Landmark.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service