This is the beginning of Neustadtgasse at the Trittligasse 16 The Trittligasse goes down to the Oberdorfstrasse. Neustadtgasse means alley in the new town and was first mentioned in 1355th.

See also in German

http://www.alt-zueri.ch/turicum/strassen/n/neustadtgasse/neustadtgasse.html