Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

Stalactites and stalagmites in a beautifully lit cave.

The magic's in the hole!

Walk 2,300 feet above the ground on the "Troll's Tongue."

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

A heavenly experience, right here on Terra Firma.

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.

New York City's smallest piece of private property.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A fifth-century temple improbably built into the side of a cliff.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

A beautiful geyser under environmental threat.

A book collector's dream, this Toronto bookstore has the world's first "Biblio-Mat," a random book vending machine.

Surreal riveted sea forts once protected the Kent shores from German attack.

Finale of "William Tell Overture" can be heard as drivers pass over grooves in the road.

The atmospheric road was never meant to be so creepy.

A Hawaiian stairway to heaven—that you can't climb.

A 140-year-old castle with underground caves hidden in San Francisco.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

Yale University's home for rare works, including the mysterious Voynich Manuscript.

Stroll through a wonderland of stupendous moss-covered trees.