As you know I love to stroll around railway stations while waiting for the next connection. So I do at airports as well. At Frankfurt on Main Airport I came across this Cadillac Sedan (1956) which is an advertisement for two German museums about technology.
Fun detail seen in Kassel: A figure standing on top of a sphere inside a church tower. Its a sculpture created by the artist Stephan Balkenhol. The traffic lights are not art, I was just standing at a pedestrian crossing and there was no time for a better position.
One my walk along the venues of the dOCUMENTA (13) I also came across the Museum of Natural History also known as Ottoneum. Outside I was impressed by its lovely architecture. Inside it was big fun to walk through a natural history collection which was one of the first to be established in all of Europe.
After World War II a large part of Kassel was rebuilt in the style of the 50ties. So if you are interested in the architecture of this period a walk through Kassel is a good way to learn more about it.