The transparent tent roof made of acrylic glass is the hallmark of the Olympic Park. At the time of its construction, it was considered the 'largest roof in the world' – a visual and structural sensation, and also a costly one. As a result, its progress was closely watched internationally. Covering an area of 78,000 square meters, the roof consists of a steel cable net suspended from pylons and supports ranging from 51 to 80 meters in height, and is fitted with acrylic glass panels. It unites the Olympic Stadium, the Olympic Hall, and the Swimming Hall – the three main sports facilities at the heart of the park. Despite its massive anchoring, the structure appears delicate and floating.
More than a dozen renowned professors were consulted as experts: structural engineers, fire safety specialists, glaciologists, ornithologists, and bacteriologists addressed issues ranging from snow load to bird protection.
In 1967, the city launched a design competition for the tent roof, which was won by the architectural group led by Professor Günter Behnisch from Stuttgart. Their concept: the main sports venues are embedded in earthen hollows, following the early Olympic model, and covered with a transparent tent roof, in reference to ancient sun sails. On October 13, 1967, 17 out of 19 jury members voted in favor of the unconventional design, which was not without controversy. To realize the tent roof idea, Behnisch and partners brought in the expertise of architect Frei Otto and structural engineer Jörg Schlaich; Otto had previously designed the tent roof for the German Pavilion at the 1967 World Expo in Montreal.
