Art Nouveau is a whimsical, elaborate style in architecture. Structures designed in the style of Art Nouveau often look more like a sculpture in a museum rather than an actual building. Designers using this style consider the windows, textiles, murals, sculpture, furniture, and artwork as part of one composition. My Modern Met created an infographic that shows different structures that can be classified as Art Nouveau. If you have no idea what Art Nouveau architecture looks like, check the infographic here!
Image credit: Theodor Vasile