Have you ever wondered how bridges don't fall down or how really old buildings stay standing up? In the How Do series, readers are welcome to guess along with the rest of us--and then explore the science behind the right answers. Basic principles of architecture and engineering are explored through diagrams, photos, and informative and engaging text. In How Do Bridges Not Fall Down?, readers will learn: - Different types of bridges and their characteristics - How column and beam structures are supported - Building techniques used in ancient buildings and why they are still standing today - How skyscrapers are built and how they are reinforced - How structures are built based on their geographic location