Greece has plenty to offer travelers from the ancient remains in Athens to the picturesque beaches on Crete to the iconic white buildings that dot Mykonos. With more than 200 islands to explore, making a choice of what to see can be dizzying. That's where a guided tour comes in. In-the-know locals can help guide you to some of the best sights Greece has to offer. Using both traveler opinion and expert input, U.S. News gathered a selection of the best tours available in Greece.