An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

The walls of the iconic dome are hollow and have a secret stairway.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

Home to items never before seen by the public.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

Forgotten and then destroyed by fire, this was once one of the largest saltwater swimming pools in the world.

One of the oldest producers of hand-folded fortune cookies still uses its original secret recipe.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

The remains of the first saint from Alaska in the Russian Orthodox Church.

Considered by many to be one of the most dangerous highways in Alaska.

Permanent exhibit reminds visitors of the Exxon Valdez.

A morbid gateway to an Alaska town prides itself on the hunting history it represents.

An Alaska livestock farm devotes itself to harvesting wool from creatures that once ran with mammoths and sabertooth tigers.

North America's first frozen mummified remains of an ice age steppe bison, the 36,000 year-old mummy named "Blue Babe."

A trading post in the North Pole where children send letters.

The king of U.S. high points towers over every other peak on the continent.

Pay homage to a preeminent matriarch, and the native Dena’ina people, at this sculpture installation in Anchorage.

In paradise, feral pigs have claimed an island all to themselves.

This little slice of old Jerusalem in Oklahoma is the evolution of a 90 year old passion play.

American bison herd descending directly from a Bronx Zoo breeding program that saved the species from extinction.

A peculiar forest that was handcrafted for government experiments.