The Musée d'Orsay in Paris houses a significant collection of Art Nouveau paintings, sculptures, and decorative arts, including works by prominent artists like Alphonse Mucha, Émile Gallé, and René Lalique.

The Museu Nacional d'Art de Catalunya in Barcelona, Spain, houses a significant collection of Art Nouveau art, including works by Catalan artists like Antoni Gaudí, Lluís Domènech i Montaner, and Josep Puig i Cadafalch.

The MAK - Austrian Museum of Applied Arts/Contemporary Art in Vienna houses a collection of Art Nouveau artifacts, including furniture, glassware, jewelry, and other decorative arts.

The Vittoriale degli Italiani in Gardone Riviera, Italy, features a collection of Art Nouveau and Decò artworks, including works by artists like Galileo Chini and Adolfo Wildt.

The Horta Museum in Brussels, Belgium, is dedicated to the preservation and display of Art Nouveau and Art Deco artworks, showcasing the works of renowned Belgian architect Victor Horta.

The Museo del Modernismo Catalán in Barcelona, Spain, houses a collection of Art Nouveau furniture, ceramics, paintings, and other decorative arts, showcasing the works of Catalan artists like Antoni Gaudí and Lluís Domènech i Montaner.

The Musée de l'École de Nancy in Nancy, France, is dedicated to the Art Nouveau movement, showcasing the works of artists associated with the École de Nancy, such as Émile Gallé, Louis Majorelle, and Eugène Vallin.

The Museo de Arte Moderno in Buenos Aires, Argentina, features a collection of Art Nouveau and Art Deco artworks, including works by Argentine artists like Martín Malharro and Emilio Pettoruti.

The Kelvingrove Art Gallery and Museum in Glasgow, Scotland, houses a significant collection of Art Nouveau and Arts and Crafts movement artworks, including works by Charles Rennie Mackintosh and Margaret Macdonald Mackintosh.

The Kunstmuseum Winterthur in Winterthur, Switzerland, features a collection of Art Nouveau and Jugendstil artworks, including works by artists like Gustav Klimt, Ferdinand Hodler, and Otto Wagner.

The Museo Nacional de Bellas Artes in Santiago, Chile, houses a collection of Art Nouveau and Art Deco artworks, including works by Chilean artists like Alfredo Helsby and Juan Francisco González.

The Ateneum Art Museum in Helsinki, Finland, is dedicated to showcasing Finnish Art Nouveau and National Romantic artworks, including works by artists like Akseli Gallen-Kallela, Hugo Simberg, and Gallen-Kallela.

The Musée des Arts Décoratifs in Paris, France, houses a collection of Art Nouveau furniture, ceramics, jewelry, and other decorative arts, showcasing the works of artists like Émile Gallé, Louis Majorelle, and René Lalique.

The Museu Calouste Gulbenkian in Lisbon, Portugal, features a collection of Art Nouveau and Art Deco artworks, including works by artists like René Lalique, Émile Gallé, and Georges de Feure.

The Riga Art Nouveau Museum in Riga, Latvia, is dedicated to showcasing Latvian Art Nouveau architecture and design, featuring exhibits on the history and development of the movement in Latvia.