Fort Mississauga, National historic site and fort in Niagara-on-the-Lake, Canada

Fort Mississauga is a fort on the Lake Ontario shore at the mouth of the Niagara River in Niagara-on-the-Lake, Ontario. It consists of a box-shaped brick tower set within star-shaped earthworks, built 1814–1816 on a foundation of brick and stone salvaged from the rubble of Newark, burned in December 1813. The blockhouse is the only original building to survive.

Built between 1814 and 1816, this fort replaced Fort George and was designed to defend against Fort Niagara across the river. Its construction followed the destruction of the nearby town of Newark during the War of 1812.

The structure was built using materials from the first lighthouse on the Great Lakes and bricks salvaged from Newark after its destruction in 1813. This reuse tells a story of rebuilding and adaptation following wartime destruction.

The fort is located on Queen Street in central Niagara-on-the-Lake and is open daily at no charge, though visitors should watch for golf balls from the adjacent course. The grounds are open to walk freely, and pathways are easy to navigate throughout the year.

The fort's blockhouse is the only original building still standing; the other structures, mostly of log, were destroyed or dismantled. Its interior is closed, but wooden staircases lead to some upper windows. The site is now ringed by the Niagara-on-the-Lake Golf Course, and the public path in starts at Front and Simcoe streets.