In 1822/23, Elector Wilhelm II of Hesse Kassel (r. 1821–1874) commissioned his court architect, Johann Conrad Bromeis (1788–1855), to build the Great Greenhouse for the cultivation of valuable tropical plants next to Wilhelmshöhe Palace. In the years 1886–1888 the greenhouse was enlarged by a tall rectangular central pavilion. Its delicate construction of iron and glass, among the earliest of its kind in Continental Europe, still makes for a striking structure even today.
Over the winter months, frost-sensitive plants known to have been cultivated here in Wilhelm's day – and, in this respect, »historical« – are accommodated in the Greenhouse. During the season (starting on 1st Advent), visitors are welcome to enjoy the riot of colour created by the orchids, palms, camellias, banana plants and other exotic specimens, bringing a hint of spring to midwinter. Once actual spring arrives (after the Ice Saints), the plants are put out into the open according to the traditional practice.