Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

Roman ruins top white travertine terraces formed by ancient hot springs.

A marvel of Byzantine engineering under the streets of Istanbul.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Clusters of huge boulders in the Australian Outback.

These Australian rock formations look like Martian beehives that have grown up out of the landscape.

This staircase full of Mayan hieroglyphics is perhaps the largest single text in the world.

Mesoamerican monoliths and zoomorphic stones covered in royal visages, ancient mythology, and grand celestial events.

Guatemalan womanizer, venerated during Holy Week.

Deep in the Guatemalan jungle stands an ancient pyramid that once marked the reign of a king.

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

This sacred cave temple is home to thousands of bats and according to legend, a giant snake king.

The name of this ancient Indonesian temple translates as "Elephant Cave" but it could be more accurately called "The Hellmouth."

Isolated atop this Balinese sea crag is a lovely Hindu temple that is said to be guarded by sea snakes.

The trunk of this 700-year-old tree measures more than 60 feet around, making it the oldest and largest baobab in Sri Lanka.

This ancient cave temple complex is the largest and best-preserved temple complex in Sri Lanka.

This elaborate temple was built around one of the Buddha's teeth.

An ancient stone fortress considered by many to be the eighth wonder of the world.

The largest game reserve in Africa is home to thousands of species but refuses to house humans.

In Zanzibar, a historic 19th-century palace is a reminder of the world's shortest war.

After sunset the heart of Zanzibar's historic Stone Town neighborhood transforms into a culinary playground.

The world's most active stratovolcano is almost always erupting.

Besides being home to cave paintings and pre-Columbian Cuban archaeological remains, you get to take a boat through this stalactite and stalagmite covered cave.