You can certainly leave Zurich Airport (ZRH) during a layover, provided you have the necessary legal documents and enough time. Switzerland is part of the Schengen Area, so if you hold a passport from a Schengen-visa-exempt country (like the US, UK, or Canada) or have a valid Schengen Visa, you can simply clear passport control and exit the airport. To make the trip worthwhile, a layover of at least 6 to 8 hours is recommended. The airport is exceptionally well-connected; the train station (Zürich Flughafen) is located directly beneath the terminal, and a train ride to the city center (Zürich Hauptbahnhof) takes only 10 to 12 minutes, with departures every few minutes. This allows you to quickly see the Old Town (Altstadt) or Lake Zurich before returning. However, remember that you must clear security again upon your return, which can take 20–40 minutes during peak hours, so you should aim to be back at the terminal at least two hours before your onward flight's departure.