Imagine you woke up one morning to find everything created by engineers had disappeared. What would you see? No cars, no houses; no phones, bridges or roads. No tunnels under tidal rivers, no soaring skyscrapers. The impact that engineering has had on the human experience is undeniable, but it is also often invisible. Structural engineer Roma Agrawal takes a unique look at how construction has evolved from the mud huts of our ancestors to skyscrapers of steel that reach hundreds of metres into the sky. She unearths how engineers have tunnelled through kilometres of solid mountains; how they've bridged across the widest and deepest of rivers, and tamed Nature's precious - and elusive - water resources.