If they push on just the right spot, even the weakest person can move this titanic boulder.

The remains of what was, not so long ago, the world's largest city.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

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

This massive subterranean fissure is known as the "underground Grand Canyon."

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

The "dragon babies" of southeastern Europe.

One of the most remote and isolated villages on the Arabian Peninsula.

Yemen's "Stone Palace" looks like it was carved right out of the tall stone column on which it is built.

Despite centuries of architectural innovation, this French castle is being built like it's the 13th century.

This family tattoo parlor has been inking religious pilgrims in the Middle East for 700 years.