Fort Ticonderoga (), formerly Fort Carillon, is a large 18th-century star fort built by the French at a narrows near the south end of Lake Champlain, in northern New York, in the United States. It was constructed by Canadian-born French military engineer Michel Chartier de Lotbinière, Marquis de Lotbinière between October 1755 and 1757, during the action in the "North American theater" of the Seven Years' War, often referred to in the US as the French and Indian War. The fort was of strategic importance during the 18th-century colonial conflicts between Great Britain and France, and again played an important role during the American Revolutionary War.
The site controlled a river portage alongside the mouth of the rapids-infested La Chute River, in the 3.5 miles between Lake Champlain and Lake George. It was thus strategically placed for the competition over trade routes between the British-controlled Hudson River Valley and the French-controlled Saint Lawrence River Valley.