One of the oldest living oak trees in the Southeast.

A remarkable geological formation resembling a forest made of stone.

Lunar landscape, a mud volcano and bizarre rock formations.

Mysterious spherical rocks in the semi-desert of western Kazakhstan.

Mount Nyiragongo has erupted at least 34 times since 1882 and is home to the world's largest lava lake.

A valley of unique erosion patterns lends to a view like nothing on Earth.

"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.

These mammoth-yet-narrow crevasses in the Earth are perfect for taking an otherworldly swim.

Watch the newest land on the planet form before your eyes.

Even King Tut was intrigued by the glass of the Great Sand Sea.

An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

The unique ecosystem atop an Australian mountain is home to some colorful inhabitants.

This strange hill on Old Fort Road where gravity works in reverse has been fascinating locals for years.

A meteorite-bounded town in Bavaria.

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

148 feet long and in the middle of a verdant forest.

400 million-year old limestone caverns nestled in the Ozarks served as shelter and a hideout for cultures throughout North American history.

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

Naturally formed rock city in Poland.

A beach made of semi-precious green sand on the Big Island of Hawai'i.

An emerald-green grotto just a short trip from Austin.

When ecosystems collide in the arid Southwest.

Extraordinary rock formations in open Peruvian fields.

A canvas of crops grow from vibrant red soil in this terraced farmland.