The world's oldest and largest museum of mass transit vehicles.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

This remote island in Iowa was abandoned after being devastated by flood.

If astronomy had a ghost, it would look like this observatory.

This former luxury resort in Kaua'i is now an abandoned relic.

The beauty of urban decay, hiding some dark secrets.

An abandoned vacation home spent a decade taking on legends. It's now taking on water.

Enchanting gardens surround a derelict mansion, all hidden in plain sight behind a stone wall.

A religious-themed park filled with folk art to bring biblical stories to life that fell into disrepair and now being restored.

Abandoned silver mine strewn with wrecked and twisted structures.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

A hillbilly theme park that proved so unpopular the land wouldn't even sell on eBay after it closed.

Four-story concrete hotel never opened to customers.

This innocuous New Mexico storefront was once the secret jump-off spot for Manhattan Project scientists.

The site of an underground detonation of a megaton nuclear bomb in the middle of the Mojave Desert.

"Not too many people can say they've had a nuclear bomb dropped on them, not too many would want to." — Walter Gregg.

The largest man-made crater in the U.S. marks the spot where we once tested mining with nukes.

This largely forgotten piece of Cold War history stands hidden in the woods just north of the Mississippi Gulf Coast.

On October 26, 1963, a 12-kiloton nuclear device was detonated here in granite some 1,211 feet below the ground surface.

The site where a nuclear bomb was lowered over 8,000 feet underground and detonated as an experiment in natural gas extraction.

This national park on the shore of Lake Michigan features remarkable dunes that lie at the heart of a Chippewa legend.

This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

A rare kind of blue bear can be found chiefly in the national park that shares their name.

This Yellowstone geyser may not shoot as high as the nearby Old Faithful, but it erupts for considerably longer.