Kuppelgewächshaus (Dome Greenhouse), Düsseldorf University Botanical Garden

The botanical garden of Heinrich Heine University Düsseldorf was founded in 1973 and laid out between 1974 and 1979 in the south of the city, near the Rhine bend at Himmelgeist. Attached to the Institute of Botany, it mainly presents plants of temperate climates on some eight hectares of open ground, and it opened to the public in 1979.

Its main glasshouse was built as early as 1974-1975, before the garden was completed. Wikipedia attributes it to the architects Georg Lippsmeier and Partner working with Karl Kraß; press coverage of its fiftieth anniversary adds that the geometry of the dome was developed by architects from the Technical University of Darmstadt.

The garden later gained two more glasshouses: an orangery inaugurated on 10 October 2004, 300 m² in area and 13 m high, used to overwinter large container plants from Mediterranean climates, and a 330 m² South Africa House opened in 2008. In 2025 the university marked both its own sixtieth anniversary and the half-century of its now iconic dome, with an exhibition planned for the occasion.

The dome is a hemisphere 36 m in diameter, rising to 18 m and covering about 1,000 m². The architects started from a half-icosahedron: each face of the icosahedron, an equilateral triangle, was subdivided into 64 smaller triangles, and optimisation of the design then reduced the whole to just ten different triangle sizes, which simplified fabrication.

The load-bearing lattice, painted yellow, sits outside the glazing. It forms 630 triangles in all, fitted with acrylic (Plexiglas) panels that bulge outwards and are held in aluminium profiles. This self-supporting structure needs no interior columns. Ninety-two triangular panes can be opened for ventilation, some of them automatically by metal rods inside the dome. As a cool house, it is kept at 12-15 °C in winter so as to reproduce the rhythm of Mediterranean climates, with wet winters and dry summers.

The dome brings together some 400 species from the world's regions with a Mediterranean-type climate, arranged in seven geographical sections; it holds plants from the Mediterranean basin, the Canary Islands, Australia, New Zealand, Asia, South Africa, Chile and California. Several species of Echium and New Zealand flax grow alongside large trees.

Some of these trees have made the dome's reputation: a New Zealand Podocarpus dacrydioides described as the only male specimen in Europe, a Taiwania cryptomerioides said to be the largest in Central Europe, which has to be pruned regularly, a kauri (Agathis australis), a threatened species in New Zealand, and Wollemi pines, specimens of which the garden received in 2008. The garden also holds a large collection of Canary Island Aeonium and 36 of the 37 species of the genus Lithops.

The botanical garden lies on the Heinrich Heine University campus in the south of Düsseldorf (Universitätsstraße 1), and the dome is its centrepiece. It is complemented by the 2004 orangery and the 2008 South Africa House, while the propagation greenhouses on the roofs of the biology institutes, used for teaching, are closed to the public.

The garden welcomes about 100,000 visitors a year and offers an audio guide. A visit to the dome extends naturally into the eight hectares of open ground, laid out as geographical gardens (alpine garden, Caucasus, Japan, China, the Americas) and ecological gardens (heath, bog, pine wood).