Art Nouveau

Art Nouveau buildings use curving lines based on plants and flowers, including the long S-shaped 'whiplash' curve. Architects exposed iron and steel in the structure and shaped it into stems and tendrils, and used large areas of glass, glazed ceramic tile and mosaic. Facades often have asymmetrical windows and doorways with rounded or irregular outlines. Designers usually controlled the interior as well, from staircases and light fittings to door handles.

Hector Guimard designed Castel Béranger, an apartment building in Paris (1895-1898), and the cast-iron and glass entrances of the Paris Métro, unveiled around 1900. In Barcelona, Antoni Gaudí remodeled Casa Batlló (1904-1906) with a facade of broken ceramic tile, columns shaped like bones and a curved roof covered in tile scales. Riga has the highest concentration of Art Nouveau buildings in the world, about a third of all buildings in the city center. The Vienna Secession used flatter, more geometric ornament, as on Joseph Maria Olbrich's Secession Building (1897-1898).

Victor Horta's Hôtel Tassel in Brussels, built in 1892-1893, is usually cited as the first Art Nouveau building. Horta left its iron structure visible and covered the stair hall's floors and walls with curving plant patterns. The name comes from the Maison de l'Art Nouveau, a gallery that the dealer Siegfried Bing opened in Paris in 1895.

The style spread across Europe in the 1890s under local names: Jugendstil in Germany and Scandinavia, Secession in Austria-Hungary, Stile Liberty in Italy and Modernisme in Catalonia. In the United States it was called Tiffany style. It reached its peak at the 1900 Exposition Universelle in Paris. Building continued in some cities after that: Riga put up 300 to 500 new buildings a year between 1910 and 1913, many in the style. Art Nouveau had largely ended by the start of World War I in 1914, and Art Deco and modernism replaced it in the 1920s.