Most buildings of the U-shaped complex which dominate the park were commissioned by the Belgian government under the patronage of King Leopold II for the 1880 National Exhibition commemorating the fiftieth anniversary of Belgian independence. During successive exhibitions in the same area, more structures were added. The centrepiece triumphal arch was erected in 1905 replacing a previous temporary version of the arcade by Gédéon Bordiau. The structures were built in iron, glass and stone, symbolising the economic and industrial performance of Belgium. The surrounding 30-hectare park esplanade was full of picturesque gardens, ponds and waterfalls. It housed several trade fairs, exhibitions and festivals at the beginning of the century. In 1930 the government decided to reserve Cinquantenaire for use as a leisure park.