Wordplay

That's the old Tempelhof airport building in the background; hoeflichkeit=politeness
(waste bins in the street are very entertaining)

Clean=happy?
There are also tiny orange streetcleaning vehicles are called Lilliputz (putzen=cleaning)

There's an U-bahn station called Onkel Toms Hutte, named after a housing estate
that was named after Harriet Beecher Stowe's book (pommes=chips/french fries)

If German puns are your thing, have a look here. Let's move on...

Flowery street in the sky...

"Farbe muss gesehen werden", said Walter Benjamin, "colour must be seen"
 ... would he have enjoyed this "farblosigkeit"?

 Some enlightenment for walkers along Am Kupfergraben ... can't find out how or why they are there...

"If anyone can do it, it's not art, and if one can't do it, then it's definitely not art."
Karl Valentin also said "Kunst is schoen, aber macht viele Arbeit" - art is lovely, but makes a lot of work

"The eye is the best tool for finding out the questions one must ask" - Peter Hauser (who he?)

"No one in the world gets to hear such rubbish spoken as the pictures in a museum" - Jules de Goncourt
and  "One waits and one always arrives late" - Peter Hauser again