Fort York is a historic site of military fortifications and related buildings on the west side of downtown Toronto, Ontario, Canada. The fort was built by the British Army and Canadian militia troops in the late 18th and early 19th centuries, to defend the settlement and the new capital of the Upper Canada region from the threat of a military attack, principally from the newly independent United States. It was designated a National Historic Site of Canada in 1923. The City of Toronto designated the site, along with the nearby Fort York Armoury, as a Heritage Conservation District in 1985.

In 1793, Lieutenant Governor John Graves Simcoe authorized a garrison on the present site of Fort York, just west of the mouth of Garrison Creek on the north western shore of Lake Ontario. Simcoe recognized Toronto was an ideal site for settlement and defence because of its natural harbour and relative longer distance from the United States. Fort York guards the western (at the time of construction, the only) entrance to the bay. Simcoe had decided to make Toronto (which he renamed York) the capital of Upper Canada, and the government, the first parliament buildings and the town were established one and a half miles east of the fort (near the foot of the present Parliament Street).

During the War of 1812, on April 27, 1813, U.S. army and naval forces attacked York from Lake Ontario, overrunning the garrison (see Battle of York). As the British abandoned the fort, they set the powder magazine to blow up, killing or wounding several hundred U.S. soldiers (including General Zebulon Pike, for whom Pikes Peak is named). The explosion was heard as far away as Fort George, rivalled only by an explosion of black powder the British set off when they were unable to bring with them said powder in their retreat from Corunna under Moore around the same time in the Napoleonic campaign in Europe. The U.S. destroyed what was left of the garrison and burned much of the settlement of York, including the Parliament Buildings during their five-day occupation. They had defeated outnumbered British, Canadian, and First Nations forces, but with the loss of many more men. Following several more U.S. raids over the summer, the British garrison returned to York and rebuilt the fortifications, most of which are still standing today. The rebuilt fort was sufficient to repel a further attempted invasion in 1814.

The British Army had occupied Fort York from 1793 but transferred the site to the Dominion of Canada after Confederation, which used the site until 1932. However, the City of Toronto owned Fort York from 1903 onwards.

Fort York was used as a military establishment until 1880, and again during the First and Second World Wars.

en.wikipedia.org/wiki/Fort_York