Viktoriahaus and Tropenhaus of the University of Basel Botanical Garden

Founded in 1589 as a medicinal herb garden for the university's medical faculty, Basel's botanical garden is regarded as the oldest in Switzerland and moved several times: from the Rheinsprung to a former monastery garden near the Predigerkirche (1692), then to the Aeschentor in 1836. It settled on its present site in 1897, beside the new Botanical Institute, on the former Spalengottesacker cemetery (1824-1868), in sight of the Spalentor gate.

The Viktoriahaus was built in 1898, during that move, expressly for the giant water lily Victoria regia, and long remained the garden's main attraction. Its centrally symmetrical, domed plan draws on the glasshouses Joseph Paxton had designed for the same plant. Rust eventually ate into the frame and damaged the panes. Recognised as a historically valuable iron-and-glass structure, the building was then restored to its original form; sources date the work to 1995 or 1996.

The neighbouring Tropenhaus, built in 1965, gave way from autumn 2019 to a new building by the Basel firm Fistarol Sintzel Jacobs, erected on the foundations and three-nave layout of its predecessor. Construction lasted until spring 2023; the official reopening took place on 26 May 2023 and an open house the following day. The budget was about 10 million Swiss francs according to the garden and 11.2 million according to the press, partly covered by donations.

The Viktoriahaus is a domed building, symmetrical around a central heated basin, whose iron frame and glazing evoke the ribs of the Victoria leaf. Its silhouette inspired the garden's logo. The basin sits at the centre of the building and carries the large floating leaves from May to September.

The 2023 Tropenhaus keeps the three-nave principle, but its volumes are taller than those of 1965, which suits large tropical plants better. An enlarged visitor foyer with a wide glazed front connects to the entrance area redesigned between the Spalentor and the glasshouse. A fourth part of the complex is the Nebelwaldhaus, a cloud forest house that visitors walk through; its climate is held between 15 and 25 °C at about 90 per cent humidity. The glass transmits UV light, and growth is so vigorous that a third of the vegetation must be removed each year. Trunks of black locust and chestnut stand in for trees to support epiphytes and climbers. A 35,000-litre tropical pond and a basin heated to 24 °C for the titan arum (Amorphophallus titanum) complete the ensemble.

In the Viktoriahaus the large basin holds Victoria amazonica or the smaller Victoria cruziana, whose leaves reach two metres across. Around it grow mangroves (Rhizophora mangle, Bruguiera gymnorrhiza), rice, floating ferns (Acrostichum aureum) and various aroids and aquatic plants.

The Tropenhaus shows bananas, palms, Brazilian bottle trees, rubber trees and Asian kapok trees, together with live animals: birds, turtles, fish, tree frogs and iguanas. The cloud forest house shelters orchids, fuchsias, bromeliads and mosses. A titan arum flowered there in late June 2023, shortly after the opening, and an eight-metre palm was relocated during construction. The garden's other houses are the succulent house, the Namibia house, the Mooshüsli (moss house) and the cold house; the garden as a whole cultivates more than 7,500 species.

The garden stands beside the Spalentor, one of the city's old gates, and adjoins several university buildings. The two main glasshouses can be seen in about an hour, longer if the other houses and the open-air collections are included.

From May to September the large Victoria leaves dominate the basin of the Viktoriahaus, the most striking season for that house. The Tropenhaus is worth visiting all year. Basel's old town, close by, is a natural continuation.