The world’s largest presentation of Gustav Klimt’s paintings lies at the heart of the collection of “Art around 1900” on show in the Upper Belvedere. Its glittering highlights are Klimt’s golden pictures Kiss and Judith, and masterpieces of Jugendstil and the Viennese Secession, which was founded by Gustav Klimt, Koloman Moser, Josef Hoffmann, and others in 1897.