Gr 4–7—A common format unites this set about the creation of these very different structures. Each book contains four chapters of varying lengths that introduce the structure and describe its inspiration, design and construction, and current efforts to preserve, protect, or maintain the functionality of the aging structures and systems. Texts are supplemented by photos of each structure, its builders and their designs, stages of construction, and cutaways and diagrams that illustrate definitions of engineering and construction processes, physical forces, and structural basics. This series is comprehensive, and the definitions and explanations of complex scientific and engineering topics are suitable for middle school readers. It will facilitate students' understanding of why each of these structures is unique and its importance in fulfilling the needs and goals of the society that built it. VERDICT A good choice for tweens interested in a mix of history, engineering, and geography.