Founded by Charlemagne in the 9th century (but heavily reworked since), Zürich's twin-towered landmark cathedral sits directly across the river from Fraumünster. The interior showcases stained-glass work by Augusto Giacometti. For far-reaching city views, climb the southern tower, the Karlsturm.

Firebrand preacher Huldrych Zwingli (1484–1531) began speaking out against the Catholic Church here in the 16th century, and thus brought the Reformation to Zürich. Zwingli’s house is nearby.