So, we lived on Hochstrasse this year in university housing. The building itself was nothing worth noting (although I did show some photos of our decorating endeavors).
After we had lived there for 9 months, my daughter and son-in-law came for a visit and pointed out this detail that we had not noticed.
It holds open the shutters! Look very closely, and you will see them at the bottom of an open shutter. (You can see that our building is in need of a paint job.)
Fun fact. A recent book called The Ministry for the Future takes place in Switzerland, in Zürich, and several of the buildings mentioned are on Hochstrasse!
Glamping in Switzerland 