Fort Niagara, also known as Old Fort Niagara, is a fortification originally built by New France to protect its interests in North America, specifically control of access between the Niagara River and Lake Ontario, the easternmost of the Great Lakes. The fort is on the river's eastern bank at its mouth on Lake Ontario. Youngstown, New York, later developed nearby.
The British took over the fort in 1759 during the French and Indian War. Although the United States ostensibly ceded the fort after it gained independence in the American Revolutionary War, the British stayed until 1796. Transfer to the U.S. came after signing of the Jay Treaty that reaffirmed and implemented the legal border with British Canada.
Wikipedia https://en.wikipedia.org/wiki/Fort_Niagara
Official website http://oldfortniagara.org/
Address 14174, United States
Coordinates 43°15'46.103" N -79°3'48.126" E