Point Mississauga Lighthouse
The first lighthouse on the Great Lakes was built of stone at Point Mississauga in 1804 by John Symington, under orders from Lieutenant-Governor Peter Hunter. Demolished in 1814 to make room for this fort, its materials with debris from the ruined town of Niagara were incorporated into this tower.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.