RAIC Awards of Excellence: Prix du XXe Siècle

A design model for Ontario Place shows the geometric Cinesphere at left, with the modular Pods suspended above the water at right. The complex was designed by architect Eberhard Zeidler, then of Craig Zeidler Strong. Photo: Zeidler Partnership Architects
A design model for Ontario Place shows the geometric Cinesphere at left, with the modular Pods suspended above the water at right. The complex was designed by architect Eberhard Zeidler, then of Craig Zeidler Strong. Photo: Zeidler Partnership Architects

Ontario Place

Completed in 1971, Ontario Place became an instant landmark for its elaborate landscape and its stunning modernist architecture by Toronto architect Eberhard Zeidler, FRAIC of Craig Zeidler Strong (now Zeidler Partnership Architects). Ontario Place crystallized avant-garde ideas in post-war architecture and urbanism, and remains emblematic of the optimistic nationalism and progressive thinking of 1960s Canada.

Originally, Ontario Place was meant to replace the Ontario Pavilion at the Canadian National Exhibition. Influenced by ideas seen at Mont-real’s Expo 67, the Government of Ontario revised its plan and decided that the site would operate independently as a brand-new inclusive environment for public entertainment, education, culture and recreation.

Zeidler, who had previously developed the ambitious Harbour City plan for the use of Lake Ontario, proposed that Ontario Place be literally inserted in and over the lake. His design consisted of two main components.

The Pods are a modular system of five interconnected mast-hung pavilions, which initially hosted an elaborate multimedia exhibition. Despite the unique aesthetic of the bridge-like suspension structure that elevates the Pods over the lake, at the most basic level, each Pod is an 8,000-square-foot, three-storey box. It can be clad in glass or steel, cut up with interior walls or floors, and have its pedestrian traffic redirected with modular ramps and bridges.

The Cinesphere is a 35-metre-wide triodetic dome made from steel and aluminum tubes. The structure is similar in design to the famous geodesic dome designed by Carl Zeiss and developed by R. Buckminster Fuller. The Cinesphere housed the world’s first permanent theatre for IMAX technology, a Canadian-made, large-format film projection system invented for Expo 70 in Osaka, Japan.

One great challenge presented by the Ontario Place proposal involved the engineering required to support it all. Initial estimates placed the cost at roughly $9 million, but Zeidler was able to reduce this figure to $900,000 by creating an artificial reef of sunken ships and lakefill around the foundations of the Pods. This approach gave Zeidler and his collaborators over 20 hectares of new land to use. The new grounds were furnished with the Forum, the Children’s Village, a marina, and a wealth of canals, walkways, and wooded areas designed by landscape architect Michael Hough.

Almost all construction materials for the project originated in Ontario: the steel for the Pods was mined and refined in Ontario, the landfill was hauled from Toronto’s booming construction sites, the Cinesphere’s architectural processes and materials hailed from Eastern Ontario, and many of the trees were transplanted from provincial lands near Barrie.

Over the years, the site was altered a number of times, which obscured the original design somewhat. In 2013, however, the Ministry of Culture, Tourism and Sport conducted a heritage study that clearly indicates that “Ontario Place is a cultural heritage landscape of provincial significance.” Accordingly, Ontario Place is now subject to the Ontario Heritage Act, and its future managed in part by a Conservation Plan respective of the Act’s Standards and Guidelines.

Ontario Place is an example of Canadian architecture at its most innovative, bold, and unusual, and represents a piece of our modernist history we are perhaps only now beginning to truly appreciate. Its Pods and Cinesphere are design treasures, but more importantly, they are cultural landmarks that possess a huge wealth of potential for the future of Toronto and the nation.

Text adapted from James Ashby and Nathan Storring’s exhibition texts for Your Ontario Place, on display at the Urbanspace Gallery in 2012.

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The Cinesphere and Pods realize—in tangible physical form—some of the most ambitious utopian architectural ideas from Europe and the United States of the 1960s, such as the sky cities imagined by designers such as Yona Friedman, and technological fantasies conceived by the Archigram group in Britain. They are a compelling example of two major design tendencies of their period: the “megastructure” and “high-tech” design.

The Ontario Place Pods’ elegant structural system, combining light tensile cable supports and compression steel masts, is superbly detailed, with very beautifully expressed connections and joints. The complex’s close relationship to Lake Ontario is celebrated through the integration of water throughout the ground plane. While the Cinesphere and Pods no longer house the functions for which they were designed, they still exhibit the same strong design presence they had when they were first completed.

The Skypod observation deck of the CN Tower under construction. Photo: Toronto Star
The Skypod observation deck of the CN Tower under construction. Photo: Toronto Star

CN Tower

When the final piece of the CN Tower’s antenna was bolted into place on April 2, 1975, the edifice became the world’s tallest free-standing structure, a record it would hold for over 34 years. Rising 553 metres above the Toronto Skyline, the CN Tower is an iconic landmark and an engineering marvel. To create the world-class structure, Webb Zerafa Menkes Housden Architects and John Andrews Architects International worked alongside engineers and contractors, innovating in design and construction methods.

The tower was conceived as a telecommunications facility. A tall structure was needed to provide high quality broadcast signals that would travel above the new skyscrapers rising throughout downtown during the 1960s. The Canadian National Railway’s solution was a TV and radio communication platform that would serve the Toronto area, as well as demonstrating the strength of Canadian industry—and CN in particular.

The CN Tower as it rises above downtown Toronto today. Photo: Nancy Rose
The CN Tower as it rises above downtown Toronto today. Photo: Nancy Rose

The original design envisioned a tripod consisting of three cylindrical pillars, linked at various heights by structural bridges. Eventually, the tower took its current form of three legs extending from a single hexagonal core. The foundation floats on bedrock more than 12 metres below ground. The tower is stable because of its mass and low centre of gravity. This allows it to withstand an earthquake of 8.5 on the Richter scale, and winds of up to 418 kilometres per hour.

Work began by constructing the CN Tower’s 335-metre-tall concrete shaft. This involved pouring concrete into a massive mold. As the con-crete hardened, the slipform moved upwards, supported by a ring of hydraulic climbing jacks, gradually decreasing in size to produce the CN Tower’s tapered contour.

Post-tensioned concrete was employed, with bundles of steel cables anchored into concrete throughout the tower. The cables run through steel ducts in the concrete core and wings. This strengthening strategy allows the structure to maintain its slender profile and gives it an expected life span of over 300 years.

To build the Skypod observation deck, a temporary steel crown was hydraulically lifted into place over a period of a week, serving as a plat-form for the necessary concrete pour. The pod was then reinforced with a large steel compression band around its perimeter.

The topping off of the antenna by helicopter became a city-wide event. While the world’s tallest tower is now the Burj Khalifa in Dubai, the CN Tower remains the tallest structure in the Western hemisphere. It has also achieved other records, including World’s Highest Wine Cellar and the World’s Highest Outdoor Walk on a Building. In 1995, the American Society of Civil Engineers named the CN To w e r one of the Seven Wonders of the Modern World.

The CN Tower has become a landmark on the Toronto skyline and a major tourist attraction, drawing more than two million visitors annually. It acts as a symbol that reminds us of a previous generation’s aspirations for Toronto as a world-class city, and an iconic image of Canada’s largest metropolis.

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The CN Tower is an incredible achievement of Canadian engineering and construction that pushed the boundaries of concrete technology and slip-form techniques to a scale never before undertaken. A timeless silhouette on the Toronto skyline, the structure has stood sentry over the remarkable development of that city’s downtown over the past four decades. It is a classic building that is a true synthesis of architectural form and engineer-ing, and one of the world’s best-proportioned communications towers.