Saint Helen's Island entered European maps in 1611, when Samuel de Champlain named it for his wife, Helene de Champlain. For decades the Le Moyne de Longueuil family held the island as private estate, until the British government purchased it in 1818 and raised fortifications after the War of 1812. Canada reclaimed the island in 1870 and opened it as a park four years later. But it was Jean Drapeau, the tireless mayor who would reshape Montreal's identity, who saw the island not as a quiet retreat but as a launching pad. He expanded Saint Helen's Island northward and southward, swallowed several smaller islands including Round Island, and created Notre Dame Island wholesale from Metro excavation fill. The engineering was audacious: barges ferried millions of tons of crushed rock downriver, dumping and shaping a landmass where only current had flowed before.

Expo 67 opened on April 28, 1967, under the theme "Man and His World." Over sixty countries built pavilions across the newly joined islands, and more than fifty million visitors streamed through during its six-month run. The American pavilion, a gleaming geodesic dome designed by Buckminster Fuller, became the fair's most iconic structure. The French pavilion, angular and modern, drew crowds for its cultural exhibits. When the fair closed, the site lingered as "Man and His World" until 1984, gradually losing pavilions to demolition and weather. Yet the bones of Expo 67 remain visible. Fuller's dome survives as the Montreal Biosphere, an environmental museum. The French pavilion found a second life as the Montreal Casino. The Canadian pavilion houses administrative offices and the studio of Radio-Classique Montreal. Even the former Tunisian and Jamaican pavilions still stand, repurposed for bike rentals and private receptions.

The park's calendar reads like an entertainment almanac. Each June, the Circuit Gilles Villeneuve hosts the Canadian Grand Prix, Formula One cars screaming past the Casino and over the bridges at speeds that would have astonished Champlain. Named for the beloved Quebec racing driver who died in 1982, the circuit weaves around Notre Dame Island's eastern half, its public roads reverting to bicycle paths when the engines fall silent. Summer weekends bring a different kind of roar from La Ronde, the Six Flags amusement park that occupies the island's northern tip. The Osheaga Festival fills August with music across multiple stages, while Heavy MTL shakes the ground for metal fans. Under Alexander Calder's towering sculpture "Man," commissioned for Expo 67, a weekly electronic dance gathering pulses through warm evenings.

Beyond the headline attractions, Jean-Drapeau Park unfolds as a surprisingly varied landscape. Notre Dame Island's western section blooms as an intricate flower garden, planted in the early 1980s on land where world pavilions once stood. The Olympic rowing basin, built for the 1976 Games and expanded for the 2005 World Aquatics Championships, stretches along the island's southern edge. Plage Jean-Dore offers Montrealers a river beach without leaving the city. Hiking trails and cross-country ski paths thread through mature trees that have had six decades to reclaim the fair's footprint. In winter, the Fete des neiges de Montreal transforms the park into a carnival of tubing, skating, and snowshoeing. A snowboard park, added in 2009, crowns a 91-metre hill built from yet more excavated earth, a fitting echo of the island's origins.

In 1999, the city renamed Parc des Iles as Parc Jean-Drapeau, honoring the mayor who had not only reshaped two islands but built the Metro that made them accessible and persuaded the Bureau International des Expositions to award Montreal its greatest spectacle. Drapeau's legacy is complicated. His grand projects strained city finances and his authoritarian style drew criticism. But standing on the park that bears his name, watching cyclists loop the Grand Prix circuit while the Biosphere dome catches afternoon light, the scale of what he willed into existence is undeniable. An entire island, fabricated from tunnel rubble, became a stage for the world and then a park for a city. Few mayors anywhere have literally built new ground to stand on.