Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

The first declared National Monument in the United States.

Continuing the tradition of the dime museum in style.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

This high point in the Great Smoky Mountains is said to be home to the chief of all bears.

The highest point in Maine is a grand gift to the state citizens that also happens to be one end of the Appalachian Trail.

This Canadian monument to the man who invented the telephone allows visitors to get up close and personal with the artifacts of his life.

From the Difference Engine to the Cray-1, all under one roof.

Guns that have been defending San Francisco since 1904.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

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

The interior of the Overlook Hotel in "The Shining" was based on this Yosemite original.

Towering basalt columns, a creation of fire and ice.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

These tourist trap caverns are said to be the former home of a legendary Pennsylvania Hermit.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

The world's longest known cave system.

Bizarre Cavern.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

14th century Norse artifacts in Northwestern Minnesota could have proved a Viking landing before Columbus.

America's largest viking stands in a Minnesota city that believes it was visited by the ancient nords.