At least seven hues of blue and turquoise make this freshwater lagoon unique.

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

These azure waters were thought to lead to the Mayan Underworld.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

This abandoned, turn-of-the-century astronomy hub is now the subject of more photographs than it ever took.

A celebration of solstice followed by a fiery purging of evils.

This 47-story "M" needed 20 years to be completed

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

This indoor ski resort has a mountain contained inside a mall.

Where Nor'easters go to die.

A massive sea stack famous for its appearance in The Goonies.

Historic psychiatric asylum and most-filmed location in the Great White North.

Defying all odds, this lonely little tree found a home on a log sticking out of a Canadian lake.

California's oldest existing theater building hosted an impressive cast of celebrities, including hosting Mark Twain's first lecture.

Commonly referred to as the most photographed Victorian home in the United States.

This massive redwood tree has a hole in the base big enough to drive through.

San Francisco's most expensive hotel suite includes a secret passageway rumored to have been used by JFK.