Witness one of the greatest bridge-building booms of all time. Three ultimate bridges call China their home: The Lupu is the longest arch bridge in the world; the Runyang is the largest suspension bridge in China (third longest in the world) and the Sutong is soon to be the longest cable-stayed bridge in the world. Tall enough to straddle huge cargo ships and strong enough to withstand powerful earthquakes and typhoon-force winds, these bridges aren't anything but mega. But to build these structures engineers have to overcome enormous challenges. They battle floods, unstable soil, strong currents, and potential ship collision. See the amazing solutions they must devise to construct three of the world's most astonishing Mega Bridges.