Bahnhofstrasse is Zurich's main shopping street in downtown Zurich. It starts outside the front of the Central Train station (Hauptbahnhof), and goes a short distance (less than a mile) and ends at the north end of Lake Zurich.
Bahnhofstrasse is famous for very high-end shopping at expensive designer boutiques--for good reason. I've never seen so many watches, chocolate shops, designer clothes and accessories, and cutlery (including Swiss Army knives of every size and function).
Cars are not allowed on Bahnhofstrasse, but pedestrians and above-ground electric trains can go door-to-door among dozens (hundreds?) of shops, cafes, restaurants, and galleries of all types.
Shops do not keep the same hours as US department stores, so do not assume they will be open on Saturdays and Sundays. Some also close during lunch. They do extend hours during Christmas time, and are open every other Sunday in December. Tip: If your visit is late or on a Sunday, or both, as with my visit, the shops in/under the Central Train station are open later than most other shops.
To find Bahnhofstrasse, go to Zurich, and take a taxi or train to the Central Train Station. Walk out the front of the Central Train Station, and Bahnhofstrasse (and shopping) starts. Take lots of money and don't walk into the path of the small quiet trains.