Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

A natural arch offers panoramic views of Yangshuo's karst hills.

A tunnel dug through the side of a mountain by hand provides convenient yet death-defying access to a small village in China.

A total of 999 stairs lead visitors through a massive hole in a mountain known as the Gateway to Heaven.

For those with no fear of heights: a skywalk 4,700 feet up on a Chinese mountain.

They squeal, they nosh, they look like predators.

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

One of the most accessible undersea plane wrecks in the world.

One of the deepest blue holes in the world.

Inhospitable caverns just beneath this island paradise offer insights into alien worlds.

Rare signs of the former Soviet Union in the Caribbean, though not where you'd expect them.

A gallery of underwater art that can be visited by man and fish alike.

The first tourist attraction to offer tours for interstellar tourists.

By standing on a particular paving stone in the courtyard, you'll hear an echo that shouldn't be.

6000-year-old coal fire moves one meter per year.

A true treehouse near Hawai'i Volcanoes National Park.

This everlasting lightning storm may be the world's largest generator of ozone.

The world's tallest slum.

Dr. Farid Mattar's Monument of Peace.

Ruins of the laboratory where a mysterious doctor invented an embalming fluid and stored his mummies.

Once the path of a railway tunnel, now home to thousands of glowing insects.

A naturally beautiful, seemingly bottomless deep blue spring.

Aqua white sand highlighted with fiery red rocks.

Australian Lake set aglow by Noctiluca Scintillans.