Plzeň—or Pilsen in German, as it's better known abroad—is the industrial heart of Western Bohemia and the region's biggest city. To most visitors the city is known as a beer mecca. Anyone who loves the stuff must pay homage to the enormous Pilsner Urquell brewery, where modern Pils-style beer was first developed more than 150 years ago. Brewery tours are available and highly recommended. There's even a brewing museum here for intellectual beer aficionados.
Another item of interest—particularly for Americans—is historical. Whereas most of the Czech Republic was liberated by Soviet troops at the end of World War II, Plzeň was liberated by the U.S. Army, led by General George S. Patton. Under the communists this fact was not widely acknowledged. But since 1989 the liberation week celebrations held in May have gotten bigger and bigger each passing year. If you're traveling in the area at this time, it's worth stopping by to take part in the festivities. To this day Plzeň retains a certain "pro-American" feeling that other towns in the Czech Republic lack. There's even a big statue here emblazoned with an enthusiastic "Thank You, America!" written in both English and Czech. You'll find it, naturally, at the top of Americká Street near the intersection with Klatovská. You can learn all about the liberation at the Patton Memorial Museum.