In 1838 plans were in place by the British Ordnance Department to establish an observatory, but it was moved to Toronto instead.

The newly formed Canadian government acquired the island in 1870; it was converted into a public park in 1874.
The public used it as a beach and swam in the river.

In the 1940s, during World War II, Saint Helen's Island, along with various other regions within Canada, such as the Saguenay-Lac-Saint-Jean and Hull, Quebec had prisoner-of-war camps.
St. Helen's prison was number forty seven and remained unnamed just like most of Canada's other war prisons.
The prisoners of war (POWs) were sorted and classified into categories including their nationality and civilian or military status.
In this camp, POWs were mostly of Italian and German nationality.
Also, prisoners were forced into hard labour which included farming and lumbering the land.
By 1944 the camp would be closed and shortly afterwards destroyed because of an internal report on the treatment of prisoners.

The archipelago of which Saint Helen's Island is a part was chosen as the site of Expo 67, a World's Fair on the theme of Man and His World, or in French, Terre des Hommes.
In preparation for Expo 67, the island was greatly enlarged and consolidated with several nearby islands, using earth excavated during the construction of the Montreal metro.
The nearby island, Notre Dame Island, was built from scratch.

After Expo 67, the site continued to be used as a fairground, now under the name Man and His World or Terre des Hommes.
Most of the expo installations were dismantled and the island was returned to parkland.
In 1838 plans were in place by the British Ordnance Department to establish an observatory, but it was moved to Toronto instead.
The newly formed Canadian government acquired the island in 1870; it was converted into a public park in 1874. The public used it as a beach and swam in the river.
In the 1940s, during World War II, Saint Helen's Island, along with various other regions within Canada, such as the Saguenay-Lac-Saint-Jean and Hull, Quebec had prisoner-of-war camps. St. Helen's prison was number forty seven and remained unnamed just like most of Canada's other war prisons. The prisoners of war (POWs) were sorted and classified into categories including their nationality and civilian or military status. In this camp, POWs were mostly of Italian and German nationality. Also, prisoners were forced into hard labour which included farming and lumbering the land. By 1944 the camp would be closed and shortly afterwards destroyed because of an internal report on the treatment of prisoners.
The archipelago of which Saint Helen's Island is a part was chosen as the site of Expo 67, a World's Fair on the theme of Man and His World, or in French, Terre des Hommes. In preparation for Expo 67, the island was greatly enlarged and consolidated with several nearby islands, using earth excavated during the construction of the Montreal metro. The nearby island, Notre Dame Island, was built from scratch.
After Expo 67, the site continued to be used as a fairground, now under the name Man and His World or Terre des Hommes. Most of the expo installations were dismantled and the island was returned to parkland.
Saint Helen's Island