Through simple text and informative photos, readers will engage with this cornerstone of transit infrastructure. Each chapter will focus on a new aspect of tunnels, such as the history of their invention, technological advances in their materials and designs, and examples of their use both in ordinary life and extraordinary situations. A follow-up activity challenges readers to put into practice what they have learned.

What are tunnels? -- How do we use tunnels? -- How do they build tunnels? -- The world's coolest tunnels.