There is an interesting house in the city of Darmstadt, which was designed by Austrian architect Friedensreich Hundertwasser. The house shows that people should live in harmony with nature even in cities. It has no straight angles, and its main feature is an unusual roof. Grass, bushes and trees grow on it and you can walk from the ground to the height of the 12th floor. Also pay attention to the windows, there are 1,000 of them in the house and they are all different! Hundertwasser designed several apartments in the house, they have no straight angles inside as well.
Look for ducklings near the house :)
Getting there: You need to get to the Darmstadt Nord train station. From Frankfurt you can go either by regional train (18 minutes) or via Darmstadt Hbf, use bahn.de. Next, you need to walk 1 km (see map). You can go one stop on any tram down the Frankfurterstrasse.