The Hundertwasserhaus is an apartment house in Vienna, Austria, built after the idea and concept of Austrian artist Friedensreich Hundertwasser with architect Joseph Krawina as a co-author. This expressionist landmark of Vienna is located in the Landstraße district on the corner of Kegelgasse and Löwengasse.

Friedensreich Hundertwasser started out as a painter. Since the early 1950s, however, he increasingly became focused on architecture, writing and reading in public manifestos and controversial essays (e.g. 1958 a ‘Mouldiness Manifesto.’ advocating natural forms of decay) In 1972, he had his first architectural models made for the TV-show ‘Wünsch dir was', in order to demonstrate his ideas on forested roofs, "tree tenants" and the "window right" of every tenant to embellish the facade around his windows. In these models Hundertwasser also developed new architectural shapes, such as the "eye-slit" house and the "high-rise meadow house"

In lectures at academies and before architectural associations, Hundertwasser elucidated his concerns regarding an architecture in harmony with nature and man. In a letter dated November 30, 1977 to the mayor of Vienna, Leopold Gratz, the federal chancellor at the time, Bruno Kreisky, suggested that Hundertwasser be given the opportunity to realize his ideas in the field of architecture by allowing him to build a housing project, whereupon Leopold Gratz, in a letter of December 15, 1977, invited Hundertwasser to create an apartment building according to his own ideas. The search for a suitable building plot took several years. Because Hundertwasser was not an architect he asked the City of Vienna to provide a professional architect willing to transpose his concepts into architectural drawings. To this end, architect Josef Krawina was invited to join the artist and to help him to put his ideas into practice.