Learn all about the great explorers of the world who have taken very brave trips to unknown places. Begin the exciting adventures of a traveler in ancient times, and learn of the achievements of the great explorers of the Middle Ages such as Marco Polo. The book describes the daring voyages of discovery in the 15th and 16th centuries, and how they changed people's view of the world. This book also sheds light on some lesser-known figures, as well as the exciting tales of exploring the north and south poles, the world's greatest mountains, and even outer space!