Which city is opposite Fort Niagara on the Ontario side of the river?

The city that is opposite Fort Niagara on the Ontario side of the river is indeed Queenstown, Ontario. Located right across from Fort Niagara, which is situated in the U.S. state of New York, Queenstown serves as a historical and geographical point of interest given its proximity to this notable fortification. Fort Niagara historically served as a significant military outpost and is key to understanding the local history of the region.

The other locations listed, such as Port Weller, Bronte, and Oshawa, are not adjacent to Fort Niagara. Port Weller is situated further away along the shores of Lake Ontario, while Bronte is located to the west of the fort in a different direction altogether. Oshawa is also considerably farther east and does not have a direct connection to Fort Niagara. Understanding this context highlights why Queenstown is the only suitable answer linked to the geographical relationship with Fort Niagara.