The Fort de l'Île Sainte-Hélène, a historic site on Saint Helen's Island that belongs to the city of Montreal, Quebec, was constructed in the early 1820s as an arsenal in the defensive chain of forts built to protect Canada from a threat of American invasion. Although not heavily fortified, it served an important purpose as the central artillery depot for all forts west. These included Fort Henry and Fort Lennox. The red stone used to build the Fort is a breccia quarried on the island, which is situated in the St. Lawrence River between the island of Montreal and the south shore.