The Waldspirale — "forest spiral" — is a residential building complex in the Kranichstein district of northern Darmstadt, completed in 2000. Designed by the Austrian artist Friedensreich Hundertwasser, it curls around an internal courtyard in a horseshoe shape, its roofline planted with trees and grass, its facade a riot of uneven windows, ceramic tiles, and bright colour.
This is architecture as anti-geometry: not a straight line in sight, no two apartments identical, the building undulating and warping as if it grew rather than was designed. The internal courtyard with its mosaic columns and fountain is accessible to visitors during daytime hours, and the building's exterior is best appreciated from the surrounding streets. Hundertwasser saw it as a protest against the "window dictatorship" of modernist housing — and the residents, reportedly, love living there.
It is not in the city centre — take tram line 9 to Berliner Allee and walk ten minutes north — but the detour is worthwhile for anyone with an interest in architecture, eccentricity, or both.