What Is String Theory? Brian Greene Explains

John Wilkes Booth knew he had to act quickly to save the South. But his original plan wasn't to kill Lincoln, it was to kidnap him

John Wilkes Booth's Original Plan to Save the South (3:14)

Before issuing the Emancipation Proclamation, Lincoln signs into law the Compensated Emancipation Act. Costing nearly one million dollars, the act buys freedom for all District of Columbia slaves.

The Act That Bought Slaves Freedom in D.C. (2:06)

Country music star Trace Adkins stops by the Smithsonian to examine some authentic sheet music from the Civil War.

Trace Adkins on Wartime Country Music (4:05)

Theodore Roosevelt made his was to North Dakota to hunt bison, it wasn't long before he fell in love with the wild, western land

How North Dakota Transformed Theodore Roosevelt (2:26)

The collection of 140,000 bat specimen at Smithsonian's National Museum of Natural History is providing a key resource for tracking the epidemic that is wiping out the world's bat population.

The Silent Killer Wiping Out This Small Species in America (2:35)

Years after all double eagles were supposedly destroyed, the Secret Service traces the reappearance of two of the rare coins back to a deal between jeweler Israel Switt and Mint cashier George McCann.

Why This 1933 Double Eagle Coin Will be Worth Millions (3:00)

Five hundred passionate Civil War reenactors gather every year to live in period tents, wear costumes and play out every step of the little-known battle.

Why 500 Men Gather in a Little-Known Louisiana Field (2:31)

Deep caves and secret tunnels provide the crocodile with a stealthy advantage in stalking its prey.(Courtesy of Paul Scofield)

Stealthy Crocodile Captures Unsuspecting Prey (2:13)

Sci-fi fan Gene Roddenberry was a freelance writer with a futuristic vision. He had high hopes for his script about a peacekeeping spaceship seeking new life forms.

How an L.A. Cop Wrote Megahit 'Star Trek' (2:34)