10 Berlin, Germany
Berlin is a multifaceted city. So feast your eyes on modern architecture, then visit a Baroque palace. Spend the day at one of the world's finest zoos, then spend the evening listening to one of the world's finest orchestras. Most travelers make a point of taking in more serious WWII-related sights as well. TripAdvisor travelers give particularly high marks to the grim but thorough and thought-provoking Topography of Terror exhibit. (via)