Extreme Engineering unveils some of the most ambitious architectural plans of our times. Some are theoretical; others are in the works. But each of these modern marvels poses challenges that stretch the definition of what's possible. Watch as jaw-dropping computer animation and first-hand accounts from builders, designers and engineers breathe life into the most extreme construction projects ever conceived. Fed up with devastating damage caused by a spate of recent floods, the Malaysian government has given the go-ahead for an unprecedented solution: construction of a six-mile long, 20-foot high storm drain directly under Kuala Lumpur - the country's capital city - that will siphon water from the city's airport to a holding pond out of town. To offset the cost of the $525 million dollar project, engineers have devised a way to enable the tunnel to serve double duty as a toll road for commuters, creating the only fast way into and out of the city.