It took five years to build. When completed in 1936, Hoover Dam was one of the world's largest hydroelectric facilities. Today, it generates 4 billion kilowatt-hours of energy a year, enough to serve 1.3 million people. An astonishing 660 feet thick at its base, the dam needs to be strong enough to store up to two years' worth of the Colorado River's average water flow.

A team of experts must demolish, excavate and recycle a 25,000 ton dam built of concrete and steel. With a century's worth of rocks and sand stacked up against it, they need a radical, dangerous plan.

Richard Hammond finds the Troll A gas platform - the largest object ever moved by man across Earth's surface - hides a farm building, racing car and a pot plant, among other elements, deep in its DNA.

A thunderous bang, heard shortly after take-off of ASA Flight 529 signals something is amiss. The situation - one of the propeller blades is now just a stub, and hanging on the left wing is a mangled mass that was once the engine. After nine minutes of keeping the plane airborne, the flight crew is forced to crash land. All passengers and crew survive the crash until a raging fire breaks out, forcing the passengers to run through searing flames. As a result, many die from their burns. Federal aviation agencies investigating the crash determine the propeller failure was caused by corrosion, the third such incident involving the same manufacturer. Their inquiries led them to conclude that the crash could have been avoided had a fatal flaw not been inadvertently covered up.