PHOTOS: The Mind-Blowing, Floating, Unmanned Scientific Laboratory

Free from their mother's care, five young lions must fend for, and feed, themselves. Their first challenge: a giant giraffe who refuses to be caught.

Incredible: Five Lions Take Down a Giraffe (2:49)

One highly influential ancient Middle Eastern civilization established some of the essential systems we still use today. Think you know which it is?

Who Decided to Put 60 Seconds in a Minute? (2:33)

In 1992, Christopher McCandless set off to test if he could survive alone in the wilds of Alaska. It didn't go as planned.

What Happened to Chris McCandless? (3:38)

In this exclusive clip from the 1930s, Confederate veterans step up to the mic and let out their version of the fearsome rallying cry

What Did the Rebel Yell Sound Like? (4:22)