In 2019, China World Horticultural Exposition in China welcomed China National Pavilion Day. The roof of the China Pavilion is "Ruyi". In order to build a roof shaped like a moon, the builders used various steel structures, including 132 main girders, 5,400 small crossbars, 2,184 tie rods, and 696 horizontal support rods. The main beam is 32 meters long and weighs 7 tons.
