Exhibition Greenhouse, Nanshan Botanical Garden (南山植物园展览温室)

Nanshan Botanical Garden covers the Nanshan hills south of central Chongqing, between 420 and 680 metres above sea level, over more than 550 hectares; its history goes back to 1954, and it is nicknamed the 'floral crown of the mountain city'. Over the decades it has grown into a set of specialist gardens devoted to camellias, roses, flowering plums and orchids, among others.

The exhibition greenhouse is described as the core project of the whole. Completed in September 2009, it opened to the public on 28 September that year. Local guides then presented it as the second-largest botanical greenhouse in China.

Eight years after opening, the building still had no official name, which made it awkward for visitors to find their way. In March 2017 the garden's management therefore launched an international call for proposals, with a 10,000-yuan prize, to name it and raise its profile; reporters then visited to describe what it holds. None of the sources consulted gives the chosen name or the author of the architectural design.

The building stands on a fully glazed steel frame with no concrete work at all. According to the Chongqing press, the main structure combines more than 32,800 steel members and 18,000 nodes, joined by more than 55,000 high-strength bolts and lifted into place in a single operation; the difficulty of the erection was likened to that of Beijing's Olympic 'Bird's Nest' stadium.

The silhouette is made up of several staggered arches, some circular and some of varying curvature, each of a different shape. The tallest reaches 26 metres, the longest 63 metres, and the maximum span is 21 metres. The clear glazing meets the plants' need for light.

The total area is 7,496 m². Four climate zones share the space: tropical rainforest (2,126 m²), four-season flowers (2,002 m²), succulents (1,024 m²) and subalpine plants (622 m²). An automated control system keeps each at a temperature suited to the plants it houses.

The figures vary: the 2017 press speaks of more than 1,500 rare species, a local guide of 2,500 introduced species, roughly 800 in the rainforest, 800 among the four-season flowers, 700 succulents and 200 subalpine plants.

The tropical zone recreates the terrain of a rainforest, with waterfalls and streams, tall trees, climbers and shade plants. It includes the wangtianshu (望天树), a species under first-class state protection in China, and a bottle tree able to store about two tonnes of water. The press also points out the miracle fruit (神秘果), which makes sour or bitter flavours taste sweet, the traveller's palm (旅人蕉), whose leaf bases hold water, the lantern tree (灯笼树) with its hanging flowers and the dragon tree (龙血树) with its red sap.

The greenhouse stands within Nanshan Botanical Garden, in Nan'an District south of central Chongqing; the building's exact position in the park could not be checked on a map.

The rest of the garden rewards a longer visit depending on the season: the plum garden, with more than 80 varieties, flowers from winter into early spring and the rose-family garden (蔷薇园: cherries, crabapples, plums, roses) from March to May, while the camellia garden gathers more than 2,000 old trees, a thousand of them over a century old. The orchid garden holds more than 8,000 pots. Former diplomatic residences, among them the old French and Soviet embassy sites, also survive within the park.