How did engineers build the tallest bridge on the planet? As tall as a skyscraper, the Millau Viaduct in southern France braves deadly wind speeds over an immense abyss, and we go inside the story behind this modern wonder.

China's Three Gorges Dam is the largest and heaviest concrete structure on earth, and it produces more power than any hydroelectric dam ever built. Discover how engineers reshaped a river to accomplish this incredible engineering feat.