Spodek

Spodek (meaning "saucer" in Polish) is a multipurpose arena complex in Katowice, Poland, opened on 9th May 1971. Aside from the main dome, the complex includes a gym, an ice rink, a hotel and three large car parks. It was the largest indoor venue of its kind in Poland until it was surpassed by Tauron Arena in 2014.
The Spodek hosts many important cultural and business events. Music concerts are especially common non-sport events. It can hold around 11,500 people, although this number is in practice limited to 10,000 or even 8,000 due to stage set-ups obscuring the view. Its Polish name refers to a flying saucer since its iconic shape resembles a UFO. Spodek is a major contribution to the cultural significance of Katowice in Poland, especially for the younger generations. It has also been used as an unofficial logo for the city on posters promoting redevelopment in Katowice. Moreover, Spodek is home to ice hockey clubs in the winter months.
History.
The idea of building a large venue originated in 1955, while Katowice was temporarily renamed Stalinogród. A contest was held to select the best design. Initially, it was to be constructed on the outskirts of town, but the Voivodeship National Council decided it should be built near the city center. A mining waste dump site classified "2A" was chosen for construction.
The classification "2A" indicated medium mining damage with a possibility of local cave-ins. While excavating the foundations, the workers dug through coal instead of soil. Soon after construction began, rumors of design flaws in the new building spread, including the rumour that the dome would collapse when the scaffolding was removed. Because of this, in 1964, construction was halted for 18 months. Spodek's architects and chief engineers entered the dome when the supports were dismantled as a response to those rumors; clearly they survived. Before opening the building to the public, endurance tests were conducted – 3,500 soldiers marched into the hall and vibration of the building was measured. The outcome was positive.
Technology.
Maciej Gintowt and Maciej Krasiński, architects of Spodek, designed the Spodek as one of the first major structures to employ the principle of tensegrity. The roof uses an inclined surface held in check by a system of cables holding up its circumference.
The structural engineer who conceived the unique tensegrity roof and made it work is Wacław Zalewski. His innovative structures include Supersam, a supermarket in Warsaw with a roof made up of alternating arches and cables, many unique industrial roofs in Poland, two basketball arenas in Venezuela with hanging roofs, the structure of the National Museum of Art in Caracas, the Venezuelan Pavilion at the Seville's Expo in 1992, and several bridges and roofs in South Korea.