It's commonly known that a single asteroid set off the dinosaurs' extinction. Even more destructive than its impact was the chain of events it set into motion.

How a Single Asteroid Wiped Dinosaurs Off This Planet (1:14)

Green tree vipers can kill in the dark. With special heat-sensing abilities, they can find prey that's all but invisible.

A Pit Viper's Sixth Sense (2:03)

Da Vinci's The Last Supper plays a key role in the 2006 blockbuster hit The Da Vinci Code. Although the film's claims are more fiction than fact, could the painting actually contain a message from Leonardo?

Does 'The Last Supper' Really Have a Hidden Meaning? (4:03)

In 1828, John Jacob Astor built a trading post on the Missouri River. Business was so profitable that it only took four decades for Astor to become America's first multimillionaire.

America's First Multimillionaire (2:49)