Fort Henry
An earlier fort was built here on Point Henry during the War of 1812 primarily to defend the nearby naval dockyard. When the Rideau Canal was built as part of a military route connecting Kingston with Montreal, the strategic importance of this site increased. The old fort was therefore replaced by the present structure of stronger and more advanced design which was completed in 1836 at a cost of over £70,000. Garrisoned by units of the British and then the Canadian Army until 1890, the fort never saw action, although it was used as a prison for rebels captured during the Rebellions of 1837-38.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.