If your preferred beverage comes right out of the tap into a frosty mug, a river cruise down the Rhine, Main, or Danube can be just the ticket. Itineraries typically visit six ports within two or three neighboring countries, which means you can sample the brews of, say, Germany, Austria, and the Netherlands all in one trip. And since European beers vary greatly in style and flavor, even the most experienced aficionados can discover something new. Check out these top port towns for beer lovers, including our picks for where you should go to raise a glass of the local brews.