Art Nouveau architecture is characterized by its use of flowing lines, organic forms, and asymmetry. It was a reaction to the rigidness of Neoclassical architecture and was popular in Europe during the late 19th and early 20th centuries.

Here are some key features of Art Nouveau architecture:

• Flowing lines: Art Nouveau buildings often feature flowing lines that are inspired by nature. These lines can be seen in the curves of the facades, the balconies, and the windows.

• Organic forms: Art Nouveau buildings often feature organic forms, such as flowers, leaves, and trees. These forms can be seen in the decoration of the buildings, the furniture, and the lighting fixtures.

• Asymmetry: Art Nouveau buildings are often asymmetrical, which means that they do not have a central axis of symmetry. This asymmetry can be seen in the placement of the windows, the doors, and the decorations.

• Color: Art Nouveau buildings are often colorful, with bright shades of blue, green, and yellow. These colors can be seen in the facades, the interiors, and the furniture.

Here are some famous examples of Art Nouveau architecture:

Casa Milà in Barcelona, Spain: Casa Milà is an Art Nouveau apartment building that was designed by Antoni Gaudí. It is characterized by its undulating facade, its organic forms, and its asymmetry.

Casa Milà in Barcelona, Spain

The Palais Stoclet in Brussels, Belgium: The Palais Stoclet is an Art Nouveau palace that was designed by Josef Hoffmann. It is characterized by its symmetrical facade, its geometric forms, and its rich ornamentation.

Palais Stoclet in Brussels, Belgium

The Horta Museum in Brussels, Belgium: The Horta Museum is an Art Nouveau museum that was designed by Victor Horta. It is characterized by its flowing lines, its organic forms, and its asymmetry.

Horta Museum in Brussels, Belgium

Art Nouveau architecture was a popular style for a variety of reasons. It was seen as a new and exciting style that broke away from the traditional styles of the past. It was also seen as a way to express the beauty of nature and the freedom of the individual.

Art Nouveau architecture had a lasting impact on Western architecture. It influenced the design of many important buildings, such as the Casa Milà, the Flower Clock, and the Glasgow School of Art. It also helped to shape the modern understanding of organic architecture.