Home to the four-day Roskilde Festival, arguably the best European rock festival, hilly Roskilde is less than 20 miles from Copenhagen. If hordes of rock stars aren't pillaging the town of 50,000, the excellent Viking ship museum is Roskilde's prime attraction. Featuring five ships discovered at the bottom of the fjord, you can add to the Viking experience by rowing the fjord on an hour-long longboat trip. The town is also famed for its much adapted 12th-century Roskilde Domkirke Cathedral.