Grossmunster
47°22′ N 8°33′ E
The Grossmünster suits anyone walking the Niederdorf market who wants the twin towers above the old town, and its trade-off is a 187-step tower climb with no lift. In winter the church opens to visitors Monday and Wednesday to Saturday 10:00 to 17:00 and Sunday from 12:00, and it closes to visitors on Tuesdays.
Photo Ank Kumar · Wikimedia Commons · CC BY-SA 4.0 and others, credited in the gallery
The Grossmünster's twin towers mark the start of the Dörfli market, which runs north from Grossmünsterplatz and Zwingliplatz through the Niederdorf. Inside, the Reformed church keeps a plain interior lit by Sigmar Polke's windows. The Karlsturm tower costs CHF 5 for adults, and the last ascent is an hour before closing.

Quick answers about Grossmunster
Is the Grossmünster in Zurich free to visit?
Yes. Entry to the Grossmünster church is free; the Karlsturm tower costs CHF 5 for adults and CHF 2 for ages 6 to 16 and students.
