This holy site either displays a centuries-old cross or a complete fake.

Five miles of underground river link lake to ocean.

Hundreds of wooden coffins dangle from cliffs and caves in the Philippines.

Bohol's mysterious brown hills.

An eatery in a shallow river where diners can enjoy their meal mere feet from the base of an artificial waterfall.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

Huge stone depressions which may have acted as an Incan agricultural experiment.

This Peruvian canyon is filled with geometric salt pools that have been being harvested since the Incan empire.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

This turn of the century masterpiece has a mysterious goaty interloper.

A still functioning vaudeville carousel that has operated for over a century boasts a colorful menagerie and past.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

San Francisco's newly reopened hands-on science museum.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Bombed and burned, this monument represents the often controversial ties between Vietnam and Cambodia.

The capital of Cambodia is named after the hill on which this ancient temple complex stands.

Khmer Rouge's high security prison.

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

A Christian monastery stands on what was once a holy Incan temple.