After the success of Apollo 11, NASA unveiled an ambitious agenda for more missions into space. But interest among the public was beginning to drop—and the Nixon administration balked at the high costs

Why Interest in Space Travel Waned After Apollo 11 (2:48)

In 1946, on a remote Pacific Island, the military began a program known as ‘Operation Crossroads.’ Its aim was to capture, on film, the actual moment of an atomic bomb detonation

Capturing a Photograph of an Atomic Bomb Blast (2:54)

The success of the Apollo 8 mission hinged on a unique and terrifying maneuver: slowing the spacecraft enough to enter lunar orbit. Even the slightest mistake would have meant certain doom

The Riskiest Maneuver in the History of the Space Program (3:51)

In July 1950, Julius Rosenberg is arrested for spying, along with his wife Ethel. Decades later, declassified documents would cast doubt on whether Ethel was guilty as charged

Was Ethel Rosenberg Wrongly Convicted as a Russian Spy? (3:10)

From the very beginning, prohibition was set up to fail. With only 1,500 agents charged with stopping the flow of alcohol into the U.S., most people continued drinking as they had done before.

Why Prohibition Was Set Up to Fail Right From the Start (1:55)

In 2003, the reverend Gene Robinson became the first openly gay bishop of the Episcopal Church. What followed was a campaign of death threats and intimidation that would test him to the core.

This Man Became the First Openly Gay Bishop in America (4:05)

It may sound like an auspicious title, but the ‘groom of the stool’ was anything but. Simply put, it was a role that entailed monitoring and assisting with Henry VIII’s bowel movements.

This Unpleasant Royal Job Came With a Fancy Title (1:59)

By 1925, a sprawling rail network had sprung into place, and more Americans could now head west to sightsee—and with five new national parks added to the roster of public lands, they had the perfect destination.

How Trains Gave Americans a Path to National Parks (1:33)

We have this image of Queen Victoria as a highly proper, disciplined monarch. But the Queen was also someone who liked to get high, from opium tinctures to chewing gum laced with cocaine.

Did This Beloved Queen of Britain Use Drugs? (2:12)

Wales is home to one of the most perfectly-preserved Roman fortifications in all of northern Europe. In Caerwent, near the southern city of Newport, sections of the original first-century Roman wall still remain.

Why Wales Is the Place to See Amazing Roman Forts (1:49)

For the chariot racers of Rome, one particular breed of horse was prized above all else: the Berber. It had a convex-shaped head, and a powerful neck that enabled it to pull the chariots at great speed.

This Horse Was the Gold Standard for Roman Chariot Racers (2:43)

Why was this tomb in Luxor's "Valley of the Kings" lacking any kind of decoration or hieroglyphics? Egyptologists believe it belonged not to a king, but another lesser royal.

Why Was This Valley of the Kings Tomb Undecorated? (2:37)

The colossal statue of the ancient Egyptian King Psamtik I was discovered in pieces—over 1,900 of them. Rebuilding it, at least partially, can help archaeologists identify his pose and the size of the statue.

Rebuilding an Ancient Egyptian Statue Is a Huge Challenge (4:00)

To most Americans, the name Benedict Arnold is synonymous with betrayal, an American hero-turned-traitor. New evidence reveals that he may have been influenced by another person: his young wife, Peggy.

Benedict Arnold and the Plot to Capture West Point (4:26)

In 1779, Gen. Casimir Pulaski's bold offensive outside Charleston, South Carolina, pushed British forces all the way back to Georgia.

General Pulaski Didn't Let His Small Stature Hold Him Back (2:02)

Originally home to the first NASA space station and post-WWII's Operation Paperclip, quaint Huntsville, Alabama is etched in history as 'Rocket City.'

How Alabama Became Home to 'Rocket City' (2:35)

Thanks to information provided by President Mitterrand of France, the U.S. knew the U.S.S.R. was stealing tech. Now, the C.I.A. had a plan - adjust the technology being stolen so it ended up sabotaging their rivals.

How the CIA Turned the Tables on Soviet Industrial Espionage (4:15)

The assassination orders found on the body of a Union colonel caused outrage in the South. But were those letters real or were they forged by the confederate government to be used as a propaganda tool?

Were the Letters Ordering the Assassination of Jefferson Davis Real? (3:27)

Despite its name, the Spanish Flu almost certainly didn't originate in Spain. In fact, it appears to have originated on the Midwestern prairies of Kansas.

Why the 1918 Spanish Flu Probably Didn't Originate in Spain (4:06)

In 1956, Nat King Cole, one of the biggest musical stars in the world, was attacked on stage by the KKK. It was the reality of being a black man in America, where even fame and fortune couldn't protect you.

The Vicious KKK Attack Against Nat King Cole (2:26)

In ancient Mayan lore, the world of the living was directly connected to the underworld: Xibalba. This belief was central to many facets of Mayan life—including a unique sport with fatal consequences.

How This Mayan Legend Inspired a Deadly Ballgame (3:13)

A team of archaeologists are trying to discover what lies beneath the medieval fortress of Castell Dinas Bran in North Wales. But instead of digging, they'll be relying on advanced technology.

Does Castell Dinas Bran Have an Arthurian Castle Resting Beneath? (3:06)

In 1936, a Harlem postal worker named Victor Green published a book that would go on to become a vital companion for African-American motorists: the "Green Book."

How the 'Green Book' Helped Black Motorists Travel Safely (2:41)

Standing in the Roman senate, Octavian read out the shocking details of Mark Antony's will. It was a devastating revelation that immediately gave the young schemer a major advantage over his soon-to-be disgraced rival.

How Octavian Succeeded in Discrediting Mark Antony (3:18)

When Octavian emerged as the sole ruler of Rome, he immediately began a sophisticated PR campaign to clean up his image. He ditched the military regalia and presented himself as a man of peace.

How Octavian Successfully Rebranded Himself (3:30)

The strict laws of Prohibition were selectively enforced, and the brunt of their legal impact fell on minority and working-class groups while vigilante groups used "Prohibition enforcement" as cover. In this way, Prohibition helped fuel the re-emergence of one of the most notorious hate groups of all time: the KKK.

How Prohibition Led to the Revival of the Ku Klux Klan (3:01)

From Radio City Music Hall to '30 Rock,' Rockefeller Center was a construction project befitting of the city's ambition. But its build was an epic affair—and came with an eye-watering price tag.

The Staggering Price Tag of NYC's Rockefeller Center (1:42)

While stars like Jimmy Stewart and Clark Gable enlisted and served during WWII, directors like John Ford would bring military footage of the Pacific conflict straight to American viewers.

How Hollywood Encouraged Recruitment for WWII (2:38)

When you look at the sheer scale of her athletic achievements, it's a wonder she's not better known today: boxing star, three-time Olympic medalist, and one of the best women's golf players of all time.

The Most Famous Female Athlete You've Never Heard Of (1:37)

The Smithsonian curator of political history talks with the co-founder of One Common Unity about creativity, education and solving the world’s biggest problems

The Long Conversation 2018: Jon Grinspan Interviews Hawah Kasat (11:57)