Did the CIA kill Bobby Kennedy?
 The Guardian UK

Bill Gates 1981
 AP Photos of the Century

Amelia Earhart
AP Photo/The Daily Rocket-Miner AP Photos of the Century

Waco, Texas 1993
 AP Photos of the Century

Unemployment Line 1938
San Francisco, California US Department of Agriculture

Mark Twain 1905
 George Eastman House

Wilbur Wright 1905
 AP Photos of the Century

Iwo Jima 1945
AP Photo/Joe Rosenthal February 23, 1945 Associated Press

Nicola Tesla
 Tesla Memorial Society of New York

Nicola Tesla 1899
 Tesla Memorial Society of New York

Nagasaki 1945
This black-and-white photo provided by the U.S. Air Force shows a giant column of dark smoke rising more than 20,000 feet into the air, after the second atomic bomb ever used in warfare explodes over the Japanese port and town of Nagasaki, in this Aug. 9, 1945 photo. The bomb killed more than 70,000 people instantly, with ten thousands dying later from effects of the radioactive fallout. This photo was made 3 minutes after the atom bomb struck Nagasaki. Associated Press

Feet Binding in China
 AFP

Plaster mold of Abraham's Lincoln's face
AP Photo/M. Spencer Green Associated Press

Mark Twain in Tesla's laboratory 1895

Giza Plateau 1918
 National Geographic

Child Labor
Scores of boys worked at the Breaker Pennsylvania Co. coal mine before child labor was finally outlawed in 1938. CNN

USS Eldridge
 National Archives

Migrant Mother
 Library of Congress

American Union Bank Run
Crowd at New York's American Union Bank during a bank run early in the Great Depression. ssa.gov

Breadline
 Encyclopedia Brittanica

"Okies" Driving to California
 Farm Security Administration

Message from the Chamber of Commerce

Children and the Sugar Beets
 National Archives

Dust Storm in Texas
NOAA George E. Marsh Album Wikimedia Commons

Obama takes office, saying choose 'hope over fear'
 Associated Press

Barack H. Obama is sworn in as the 44th president
Chuck Kennedy-Pool/Getty Images Boston.com

Mother Jones
Mary Harris "Mother" Jones Wikipedia

Berlin Wall 1962
 Boston.com

The Wink

Mining in Kentucky
By Russell Lee, Field, Bell County, Kentucky, August 31, 1946 National Archives

Queen Elizabeth's Diamond Jubilee
John Stillwell/Pool via AFP/Getty Images