1953: Julius and Ethel Rosenberg, accused of cold war espionage, are executed. The Rosenbergs had been found guilty of conspiring to leak atomic bomb secrets to the Russians, but the accusations were controversial, and today many Americans believe their death sentences were a miscarriage of justice.

Today: Robert Philip Hanssen, a counterintelligence specialist and FBI veteran, is accused of selling secrets to Russia for $1.4 million in cash, diamonds, and deferred money. If convicted, he could face the death penalty.

1955: Disneyland, part of the empire that Walt Disney built, opens in California, the first theme park in America's history of leisure.

Today: The Walt Disney Company is a multibillion dollar entertainment giant, operating theme parks all over the world, including Great Britain, Japan, France, and Australia.

1959: Anthropologist Louis Leakey finds the skull of "Nutcracker Man" in Olduvai Gorge, Tanzania, suggesting that human evolution began on the...