Since the 1950s Hundertwasser has expressed his concern for a more humane architecture in harmony with nature with numerous manifestos, demonstrations, actions and models of exemplary architecture. He called for a boycott of functional architecture and demanded creative freedom of construction and the right to individual building alterations. In the 1980s, his architectural projects attracted international attention and triggered an architectural discussion. Hundertwasser's architectural projects include window right and tree tenants, the uneven floor, forests on the roof and spontaneous vegetation.