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. Often a huge calamity is traced back to a tiny cause, insignificant in itself, but triggering a domino effect. We'll revisit notable disasters and search for probable causes.

Engineering disasters can result in personal tragedy, national humiliation, and economic ruin. But buried within their wreckage lie lessons that point the way to a safer future. The fire at the Las Vegas MGM Grand Hotel, the collapse of Seattle's Lacey V. Murrow Floating Bridge, the car that spurred creation of the National Highway Transportation Safety Administration, and the flaw that grounded the first commercial jet are among the engineering disasters that led to improvements in design and safety.

Engineers and architects reveal what went wrong in five engineering disasters, including Baldwin Hills Dam that suddenly gave way, spilling liquid havoc in a quiet LA neighborhood; a mysterious plane crash that killed all aboard (Lockheed Electra); a massive freighter's shuddering crash into Tampa Bay's Sunshine Skyway Bridge; the 1994 Northridge, California earthquake that shook down poorly engineered buildings; and a 4-decade old coal mine fire that turned Centralia, Pennsylvania into a ghost town.

Join us for a devastating but enlightening hour as we delve into complex and often-tragic engineering failures that have shaped our world. Five dramatic events unfold as we discover the causes of: the 1983 collapse of New England's Mianus Bridge; the sinking of the Ocean Ranger offshore oilrig in 1982; the crash of a Learjet 35 private plane carrying pro-golfer Payne Stewart in 1999; the 19th-century failure of South Fork Dam that resulted in the flooding of Johnstown, Pennsylvania; and the 1988 PEPCON (Pacific Engineering Production Company of Nevada) jet fuel plant explosion.

It's another chapter of complex, deadly and controversial engineering failures, using 3-D animation, forensic engineering experts, and footage of the actual disasters to understand what went wrong, and how disaster has led to improvement. In Sun Valley, California, weeks of record rain turn a crack in the middle of a street into a 200-foot long sinkhole. Months later, rain led to the Laguna Beach, California landslide, which destroyed 11 homes and caused millions in damage. On May 23, 2004, four people were killed when the roof of the new Terminal 2E at Charles de Gaulle International Airport in Paris collapses. Other disasters: the 1931 crash of Fokker F-10 passenger airplane with coach Knute Rockne aboard; the sinking of the coal ship Marine Electric off the coast of Virginia; and the blinding reflection of the new Walt Disney Concert Hall in Los Angeles.

We look at a 1999 tragedy, when three ironworkers plunged 200 feet when the basket in which they were working was struck by debris during construction of Milwaukee's Brewers Baseball Stadium. Next, we travel to a deadly explosion in China's Sunjiwan coal mine--antiquated equipment, minimal safety standards, and a rush to overproduce left the mines susceptible to fires, floods, and explosions. From the 1920s through the `50s, US shoe stores featured the fluoroscope. Based on an early Edison machine, the fluoroscope took x-rays to determine a customer's size--while emitting high doses of radiation. In California, we visit the Salton Sea, an unnatural body of water with no drainage that grows more salty and less hospitable to life daily. In the 1950s Soviet leaders embarked on a massive irrigation project that diverted water from the Aral Sea. Over time, the coastline receded 100 miles, killing off many species of fish and a once thriving fishing industry.

Examine one of the most mysterious maritime tragedies, when the sturdy Edmund Fitzgerald suddenly sank on a stormy night in November 1975; and unlock the mysteries of the rudder problems behind two Boeing 737 crashes--a 1991 United flight and 1994 US Air flight. Then, we take viewers inside one of the most dangerous but least-known nuclear disasters in US history--a meltdown at a secret government facility in 1959. We also travel to an oil storage facility where nearly 4-million gallons of diesel fuel suddenly flowed out as the storage tank cracked and catastrophically unzipped from top to bottom. Finally, we take a "close look" at microscopic structures causing gigantic problems in the electronics industry--tin whiskers, as they are known by researchers, that spontaneously grow from pure tin coatings on electronic boards and microchips.

When design flaws fell projects, the cost is often exacted in lives as we see in this look at engineering disasters. Why did the Tower of Pisa begin to lean by as much as 17 feet; what caused the first nuclear accident in 1961 in Idaho.