Ha Long Bay's "Cave of Surprises" houses a popular phallic rock formation.

Khmer Rouge's high security prison.

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

A battle between nature and architecture in the Cambodian jungle.

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

To gaze upon the visage of Sri Lanka's biggest Buddha, one must first pass through the Tunnel of Hell.

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

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

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

Modest by day, illuminated majestically at sunset.

At 8,000 feet, the world's highest tea estate draws visitors for both its products and its panoramic views.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

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

The 953 windows undoubtedly make this the world's most beautiful screened porch.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

A sharp bend in a dramatic river canyon cut through red rocks.