For four years, Yvonne Morris worked at Missile Site 571-7. Literally, it was a real hell hole.

Deep underground in a high-security control room, she and her crew held the keys to an apocalyptic hammer -- a nuclear rocket that could flatten an entire city in just 30 minutes.

"I know I would have been able to launch, if ordered," said Morris, an ex-Air Force lieutenant. "But if we launched, then life as we know it was over."

Based near Tucson, Ariz., during the 1980s, Morris joined thousands of steely-eyed missile-men and women who helped bring a peaceful end to the Cold War.

The silo -- now the Titan Missile Museum -- is one of hundreds of American travel destinations that honor the nation's history of military readiness and sacrifice.

How about a fire-spewing WWII battle re-enactment with an actual flamethrower? Or a massive warship that saved 3,000 refugees? Or a training ground for some of the toughest fighting men and women in the world?

Titan Missile Museum

Of all these magnets for the military enthusiast, one thing sets the Titan museum apart: It's the world's only remaining underground installation housing an actual Titan II missile.

"It's not a mockup," says Morris, who's now the museum director. "It's the real deal. Except," she laughs "there's no warhead."

That's probably a good thing, because the Titan II carried the nation's deadliest nuclear warhead -- equal to more than 9 million tons of dynamite.

During its heyday from the 1960s into the 1980s, more than 50 Titan II launch sites dotted Arizona, Kansas and Arkansas. Decades after the Cold War, enthusiasts can now snuggle up close and cozy with a doomsday device.

A special observation deck at the museum allows a breathtaking view of the rocket from tip to tail.

HGTV addicts take note: The underground bunker is designed to rock and roll.

Literally, because the whole complex is cushioned by giant springs.

The floors are separate from the walls so the facility can survive giant shock waves from, say, an earthquake, or perhaps an enemy nuclear missile attack. Careful! When you step into a room, don't trip over the 11-inch gap in the floor. That's called the "rattle space."

Oh, and it's not every day that you can see humongous steel blast doors weighing 3 tons. Don't forget to shut the door behind you on the way out.

On the whole, life in the hole wasn't bad, to hear Morris tell it. Several four-person crews each rotated 24-hour work shifts in the underground habitat. Surprisingly, it was hard to get bored, she said, because they just "drilled and drilled and drilled." Performing equipment maintenance, testing circuits and systems and monthly training, testing and evaluation.

A quarter century after the site was decommissioned, it still holds secrets. We still don't know exactly where the missile was pointed. That's classified.

Did the missile site ever come close to launching? Also classified.

Those untold secrets are shared by the launch crews and their chains of command. We'll likely never know.