Did you know that a bridge made of 104,500 water bottles spans Romania's Bega River, or that the first underground railway opened in London over 150 years ago? We have needed ways to cross valleys, rivers, and mountains for as long as there have been people on Earth. Over time, scientists and engineers began to understand the laws of nature that apply to bridges and tunnels. They understood the strengths and weaknesses of materials better, too - and began to create new ones, like concrete and steel. This fascinating guide to bridges and tunnels explores unique examples of each, what they're made of, and all of the unexpected twists and turns taken in their development. Features include funny and interesting illustrations; real-world science examples; side panels to tackle complex subject matter in a fun and relevant way; detailed glossary and more.