Niagara-on-the-Lake or Niagara, town (1991 pop. 12,945), S Ont., Canada, on Lake Ontario at the mouth of the Niagara River. It was settled (1784) by American Loyalists and in 1792 Lieutenant Governor Simcoe made the town the capital of Upper Canada, renaming it Newark. The legislature met there until 1796. Fort George, built (1796–99) to defend the settlement, was taken in 1813 by the United States but retaken in the same year. The town, officially called Niagara-on-the-Lake to distinguish it from the Canadian and U.S. cities of Niagara Falls, is an architectural and historical treasure, with many well-preserved 19th-century buildings. It is the site of the Shaw Festival, an annual theater festival.