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Location: Montreal, Quebec, Canada
Completion Date: 1976
Cost: $1 billion
Diameter: 340 feet by 575 feet (elliptical)
Type: Cable-supported roof
Materials: Plastic, concrete, steel
Engineer(s): Les Consultants du Stade de Montréal
Built for the 1976 Olympic Games, Montreal's Olympic Stadium was one of the first sports stadiums to be capped with a plastic dome roof. But it wasn't an immediate success. In fact, the stadium was only partially completed before Montreal hosted the Olympic Summer Games. After the Olympics, the Quebec government attempted to finish the structure, but cost overruns and unsolved engineering problems stopped the project in its tracks.
Most of the problems stemmed from the retractable roof system and its mast, a 556-foot leaning tower adjacent to the structure. In 1986, engineers were forced to change its structural system from concrete to steel after a study showed that the tower would be too heavy if completed in concrete. In 1987, engineers finally capped the stadium with 60,696 square feet of orange and silver Kevlar fabric, a synthetic fiber used in some bulletproof vests. Hoisted by 26 steel cables, the enormous fabric roof was supposed to fold into the adjacent leaning tower, much like a giant umbrella -- but it didn't. From mechanical failure to rips and tears, the Kevlar membrane roof cost $700,000 in annual upkeep.
The roof of Montreal's Olympic Stadium remained permanently closed for several seasons. Finally, by the spring of 1998, the problematic orange Kevlar roof was replaced with a $26 million nonretractable, opaque blue Teflon-coated Fiberglas fabric. All told, Montreal's Olympic Stadium cost more than a whopping $1 billion to build.Here's how this dome stacks up against some of the biggest domes in the world.
(diameter, in feet)