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

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

This vertical pinnacle in China was the inspiration for the floating mountains in the movie “Avatar.”

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

Raging waters have created a strange geological site that looks like something off of a progressive rock album cover.

After millennia of erosion by sand and churning water this Brazilian valley now looks like a lunar fantasy.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

This extraordinary geological oddity resembles human-made pavement.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

This nine-story building can be played like an instrument.

A psychological self-portrait in the form of a giant, segmented head.

This tea house was a hand-built gift from Boulder's sister city in Tajikstan.

In the middle of a suburban Denver neighborhood is a cave that once provided solace for a prominent Ute chief and his family.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

The childhood home of Henry Jones Jr. is now an adventure-themed bed and breakfast.

This popular pilgrimage site offers a hole filled with holy healing dirt.

Years of archaeology, just chillin' by the water cooler.

These pretty kitties killed and ate as many as 135 railway workers.

No one knows how many bodies are in this vault in a Chicago public park.

A monument to the art of slicing people open.

A curious collection of miniatures in a quiet corner of the Chicago Children's Museum.

To find the "unicorns of the deep" you've got to go downstairs.

One artist's yard is full of shining, whirling kinetic sculptures that look like pure steel psychedelia.