Khmer Rouge's high security prison.

Highly spherical boulders on the shores of New Zealand.

Major tourist destination known for its bubbling mud-pools and hot thermal springs.

Tubing through a cave lit with glowworms is a magical underground experience.

A 17th-century mosque that was used for war more than worship.

Holy Hindu shrine in an enormous, monkey-filled limestone cavern.

A phallic shrine to a princess goddess in Krabi, Thailand.

5,000 skulls in memorial to those killed by the Khmer Rouge.

A battle between nature and architecture in the Cambodian jungle.

This Himalayan airport provides one of the most difficult landings in the world.

Myanmar's Mount Olympus atop a 2,500-foot volcanic plug.

Sacred Buddhist home of some spiritual monkeys.

The small cliffside monastery known as the Tiger's Nest is said to be the meditation site of an eighth-century Buddhist master.