Following up on this posting, I’d like to suggest that a great city is not only clean but also beautiful. Driving/walking around here in Zurich, I have seen many nicely decorated apartment balconies as well many beautiful gardens, for example. Actually, I cannot think of a city, that I have been to, where so many balconies of apartments are so nicely decorated with flowers.
I took the photo below some days ago, as I visited Stadtgärtnerei Zürich, which is located here. You can find some more photos from the place here.