From the record
“Fort Michilimackinac was an 18th-century French, and later British, fort and trading post at the Straits of Mackinac; it was built on the northern tip of the lower peninsula of the present-day state of Michigan in the United States. Built around 1715, and abandoned in 1783, it was located along the straits that connect Lake Huron and Lake Michigan of the Great Lakes of North America.”
Wikipedia article Fort Michilimackinac, CC BY-SA 4.0.
One of 49 National Register listings published here for Emmet County · listed in 1966 · category: Site · a National Historic Landmark.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service