The Grüne Zitadelle (or Green Citadel, in English) in the central German city of Magdeburg is a startling, whimsical, fanciful complex of apartments, shops, cafés, a hotel, and even a kindergarten. The last design of the late Austrian “alternative architect” Friedensreich Hundertwasser, he called his big pink project an “oasis for humanity and nature in a sea of rational houses.”

The striking building took two years to complete, and was christened in 2005. If it looks irrational, it’s mostly by comparison to its neighbors in and around Magdeburg’s Cathedral Square. Here there is a mix of Baroque and classical styles, as seen in its Gothic cathedral, 11th century Romanesque monastery, and the State Parliament. But none of those are pink, and zero sport a roof made of grass.

As one of the first prefabricated slab buildings constructed in Germany, its style, color, sensibility, and construction methods have all come together to help transform the otherwise staid central district of this small city. In the course of this one block’s transformation, Hundertwasser’s crowning architectural achievement fits into the unique ensemble of old edifices, and what you might call middle aged (many might call cold) post-war architecture seen in some of the vicinity’s commercial buildings. But the Green Citadel has snuggled right in, while at the same time remaining the antithesis of both.