Hector Guimard was a French architect known for his Art Nouveau style. Some of his most iconic works included Castel Béranger, an apartment building in Paris designed in 1895. For this project, Guimard designed every detail himself, from furniture to wallpaper. He also designed the entrances for the Paris Metro from 1900 to 1913, using cast iron and glass inspired by plant forms. Guimard helped popularize the Art Nouveau style through his distinctive architectural designs.