Those who just stumble upon the Hundertwasserhaus apartments in the Third District will likely be wowed by the buildings. Friedensreich Hundertwasser’s funky, mid-1980s organic housing complex is weird and gorgeous with a wavy, eclectically painted facade that looks like something out of a cartoon. With trees growing on its terraces and roof, it’s the antithesis of staid imperial Vienna. A freethinker if there ever was one, the artist, architect, and environmentalist Hundertwasser could be called Austria’s Gaudí. Visitors can learn more about him in the ground-floor café. Nearby, Hundertwasser designed the Kunst Haus Wien art museum out of an old Thonet furniture factory, while up the Danube Canal an incineration plant’s chimney got the Hundertwasser treatment with trippy colors and a funky golden ball on top.