The Casa Mila in Spain is an example of art nouveau architecture.
Art nouveau is a style of art that was prominent in Europe and the United States from the 1880s until about the beginning of the first World War. The style was prevalent in jewelry, paintings, furniture and architecture. It was a movement begun by several key artists who were rebelling against the neoclassical art movements of the past, which were heavily based on symmetry and geometric forms.
Asymmetry
Because art nouveau was a rebellion against the geometric forms and symmetric elements of the movement that preceded it, neoclassicism, one of its main characteristics is asymmetry. Many art nouveau buildings exhibit a quality of surrealism with bends and twists not typically found in buildings made before the movement.
Arches and Curves
Many art nouveau buildings exhibit arches and curved forms. These make the buildings exhibit a more surreal and modern look, again, in direct opposition to art nouveau's preceding movement, neoclassicism. A few prime examples of arches and curves used in art nouveau architecture include the entrance to the Paris Metro (subway), the Synogogue de la Rue Pavee and Musee d'Orsay.
Plants
Much of art nouveau architecture also used plant-like tendrils and reliefs in the architectural designs. Oftentimes, these homages to plants were curvy and asymmetrical, keeping with the art nouveau theme. Another reason plants were used was to make a statement about neoclassicism and its attempts to create beauty through human-made designs. The plants were a symbol of the true beauty found in nature.
Materials Used
The materials used to create art nouveau buildings were as unique as the structures themselves. For the first time ever, materials such as bricks, ceramics, glass and iron were being used in new ways -- being bent, twisted and curved -- purely for aesthetic purposes, and having little or nothing to do with functionality. One of the most famous structures in the world, The Eiffel Tower, was born from the revolutionary use of these "new" materials.
Key Players
The art nouveau movement is accredited to a man named Siegfried (Samuel) Bing. The opening of his museum, Le Maison de l'Art Nouveau, began displaying the new style and sparked the movement. Another key architect was Victor Horta, who created the Hotel Tassel in Brussels, considered by many to be the first true art nouveau building. Hector Guimard is also considered to be one of the forefathers of the art nouveau movement. He designed the entrance to the Paris Metro, as well as the Synagogue de la Rue Pavee.