There are the well-known tales of American turncoats working for the Russians

In November 2007, Russian President Vladimir Putin raised a glass with his military intelligence officials to honor and celebrate an American named George Koval.

Koval, the son of Russian immigrants, was born in Iowa in 1913. He loved baseball. After becoming a chemical engineer for the U.S. Army, Koval was hired to work on the Manhattan Project.

He was also a Russian spy.

After his death, in one of the great stick-a-thumb-in-the-eye episodes in Cold War history, Putin outed Koval to the world by clinking champagne glasses and posthumously awarding him Russia's highest honorific tile: Hero of the Russian Federation.

Koval's story is told at the Wall of Spies Experience, a new museum inside the very secure headquarters of the National Counterintelligence and Security Center, which guards against intelligence threats and insider espionage.

Like the CIA's museum at its Langley, Virginia, headquarters, the Wall of Spies Experience cannot be visited by tourists.

But that's also part of the point.

In showing off the museum earlier this week to background-checked reporters, NCSC officials said the stories told of more than 135 spies who betrayed America is a humbling lesson on the importance and difficulty of counterintelligence operations. It's also a tacit nudge to intelligence workers: Don't wind up on this wall.

NCSC Director William Evanina called the exhibit a "daily reminder" that there are Americans on U.S. soil willing to betray their country - always have been, always will be.

The Wall of Spies Experience cannot be visited by tourists.

"We're in the counterintelligence business to prevent this," he said.

The museum, made up largely of individual stories told on a wall in a long corridor, begins with the story of John Jay, the Founding Father credited with running America's first counterintelligence operation - stopping a British plot to kill Gen. George Washington. It ends with Kevin Mallory, a former CIA officer sentenced in May to 20 years in prison for spying for China.

In between, there are the well-known tales of American turncoats working for the Russians: Julius and Ethel Rosenberg, executed in 1953; Alger Hiss, a State Department official; and Aldrich Ames, a CIA double agent arrested outside his Virginia home in 1994.

But there are also non-household spy names. Koval, for one.

William Weisband is another. Born in what was then the Russian Empire in 1908, Weisband and his family immigrated to the United States in the 1920s. The Soviets recruited him when he made a trip to his homeland in 1934. Weisband became a linguist in the Army's Signal Security Agency - and a handler for other Soviet spies. His entry on the Wall of Spies says:

"Weisband proved to be a devastating spy. He tipped off the Soviets about the existence of VENONA - a highly classified program that exposed numerous American traitors by decoding commercial messages sent between Moscow and Soviet missions abroad - after literally peering over the shoulder of America's top codebreaker as the first intercept was decrypted. By alerting his Soviet contacts, Weisband prevented the decoding of thousands of other intercepted cables. He also betrayed the greatest U.S. intelligence success of the time - ASA's ability to intercept and decode five other Soviet military and civilian encrypted communications systems."

Weisband was ultimately discovered, his wall entry says, "but because incriminating evidence could not be introduced in open court, he escaped espionage charges." Facts not included in his entry: He worked the rest of his life selling insurance and died after suffering a massive heart attack while driving on the Washington area.

In addition to spy stories, there are spy artifacts: the colored chalk and thumb tacks double agent Robert Hanssen used to signal to his Russian handlers; decoding machines and hidden cameras; and the arrest record and fingerprints of John Walker, a U.S. Naval officer whose two decades of spying began when he walked into the Soviet Embassy in Washington to sell documents.

There is also a map of 21 secret meeting places in the Washington area.

And then there are the code words the Soviets used to describe their American counterparts.

Balloon = Atomic bomb.

Hammer = Soviet Union.

Liberal = Julius Rosenberg.

And then there's Crook, a favorite of NCSC Executive Director Patty Larsen.

Who was Crook?

Rep. Samuel Dickstein, D-N.Y., who was paid $1,250 a month in the 1940s to pass congressional secrets to the Soviets, while also helping obtain illegal visas for communist operatives.

He was known for being a particularly greedy Soviet asset, which is how he got the name Crook.

"That was a nice touch," Larsen said, tipping her intelligence cap to the Russians.