One of a series of books that look at different topics on a design and technology basis, this book, dealing with bridges and tunnels, asks: what is its purpose; how is it put together; what is it made of?; and how does it work? Related craft activities help the reader to discover the answers and they are also encouraged to contribute further development of the design and technology demonstrated by the craft project. There is also related information about the historic development of bridges and tunnels, and different designs worldwide.