Among the most prestigious projects and best-known projects in contemporary architecture are the stadiums for the Olympic Games, whose architects are chosen by highly publicized international competitions. The Beijing National Stadium, built for the 2008 Games and popularly known as the Bird's Nest because of its intricate exterior framework, was designed by the Swiss firm of Herzog & de Meuron, with Chinese architect Li Xinggang. It was designed to seat 91,000 spectators, and when constructed had a retractable roof, since removed. Like many contemporary buildings, it is actually two structures; a concrete bowl in which the spectators sit, surrounded at distance of fifty feet by a glass and steel framework. The exterior "Bird's nest" design was inspired by the pattern of Chinese ceramics. The stadium when completed was the largest enclosed space in the world, and was also the largest steel structure, with 26 kilometers of unwrapped steel.