Creepy catacombs, ancient aqueducts, unbelievable underwater roadways...get readers ready to explore some of the oldest, longest, deepest, and spookiest tunnels on Earth. Readers will learn engineering concepts while investigating mind-blowing tunnels around the globe. From the terrifying catacombs of Paris to futuristic underground highways, they'll be amazed at these marvelous tunnels. Gorgeous photographs bring this globetrotting journey into splendid focus, while snappy fun facts keep the text accessible. Fun and informative graphic organizers help readers understand important STEM concepts.