Modern Marvels: Engineering

Explore the series of events that led to one of the worst industrial accidents in the United States, look at what went wrong with NASA's Skylab in 1974, and examine the fire that destroyed a gas company in 2005.

Standing majestically for centuries, great pyramids have long inspired and mystified scholars. Leading experts and historians explore the engineering genius that created some of the largest structures on the planet.

The engineering marvel Machu Picchu sits perched on a ridge in the Peruvian Andes. Originally built by the Incas, this magnificent structure remains a mystery. Was it an observatory? Pleasure retreat? Fortress?

It's clear from the bow that nearly brought down Rome, the suspension system that revolutionized the chariot, and the axe that named a country that barbarians and technology aren't such a contradiction after all.

A steam pipe explosion rocks a summer day in Manhattan; Boston's Big Dig highway project suffers a major setback; rush hour in Minnesota turns deadly as a bridge plunges into the Mississippi River.

Discover the incredible tale of how Gutzon Borglum created the world's largest sculpture by carving the faces of four U.S. presidents into the Black Hills of South Dakota.

Winding 6,000 kilometers through undulating mountains, it is said to be visible with the naked eye from the moon. But who called for the Great Wall's construction? And how was it accomplished?

Supporters see it as key to a new China, but critics voice a litany of concerns. Trace the story of China's Three Gorges Dam from ancient flood control to current controversy.

Rare photographs and behind-the-scenes stories recall the politics, the struggles, and the tragedies that made possible an engineering feat of almost miraculous proportions.

Learn how development of electricity and indoor plumbing made skyscrapers possible as the veins and arteries of the California Department of Transportation headquarters in LA are installed.

In hour three of a crash course on mega-skyscraper construction, take a closer look at the human element involved in the development of systems like air conditioning and pressurized elevators.

From the Colossus of Rhodes and Egypt's pyramids to the Hoover Dam and the Space Shuttle, mankind has celebrated the work of engineers. But what happens when their calculations prove wrong?

Death seeps out of the ground into a neighborhood sitting on a toxic waste dump; soldiers die due to software flaws during Desert Storm; the science of demolition is put to the test - and fails.

A deadly accident traps hundreds in a smoke-filled Alpine tunnel; three boilers explode on a Mississippi riverboat; a cockpit warning system malfunctions, causing a crash before the jetliner ever takes off.

To err is human, but when the error results in the loss of life, it's a disaster. Learn about the sinking of the Edmund Fitzgerald, the Buffalo Creek Dam disaster, and the explosion of a tanker in Los Angeles harbor.

Throughout history the same builders and engineers that paved man's path out of the caves and into the modern world also caused some of mankind's worst disasters. Revisit notable disasters and their probable causes.

Built of stone, glass, persistence and prayer, gothic cathedrals are an epiphany of imagination and an articulation of joy, including Chartres, Notre Dame and the National Cathedral in Washington D.C.