I am always taken aback when I see the Limmat River, which runs from Lake Zurich through the center of Switzerland’s most populous city. It’s crystal clear and looks clean enough to drink. According to Zurich’s detractors, the city’s cleanliness can verge on sterility, but I never fail to enjoy myself there. The surprisingly friendly town — despite its population of nearly 1.5 million, it often feels more like a large town than a city — has a hilly medieval center of winding lanes, a thriving restaurant scene and a picturesque lakeside setting backdropped by snowy Alpine peaks.