The Augustinerkirche is a small Gothic church on Augustinergasse, a few steps off Bahnhofstrasse. Built from 1270 onwards as the church of an Augustinian friary, it lost its monastic context after the Reformation and was used for a time as a workshop and even a coin mint. In 1843 it was restored and given to the Christ Catholic (Old Catholic) congregation, which it still serves today.
The interior is small but elegant — a simple Gothic nave with a wooden barrel-vaulted ceiling, plain limewashed walls, and a few modern stained-glass windows that work well against the medieval shell. Worth a five-minute look if you are exploring the Augustinerquartier; the surrounding streets are some of the prettiest in the old town and were largely missed by the post-medieval rebuilding that altered other parts of central Zurich.