This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Outsider art meets paleontology at this roadside reptile repository.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The headquarters of the Mahanikai school of Buddhism, Thailand's largest monastic order.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Every equinox this Maya pyramid puts on a spooky ancient light show.

A turquoise lake within a volcanic crater.

A serene space tucked amid the skyscrapers of Hong Kong's bustling financial district.

Climb to the top of the world's largest seated bronze Buddha.

Teeming with illegal goods and services, this towering maze of vice is also a popular tourist accommodation.

The world’s largest LED display, built over an F1 race circuit.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

A faithful reproduction of Al-Jazari's enormous water clock.

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

Whitewashed mosque contains the world's largest carpet.

A fountain standing as a testament to a doomed alliance.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

This bazaar is one of the oldest in the Arabian world.

Skyscraper powered by wind turbines attached between its towers.

This beautifully historic Bahrain fortress might not be the most popular attraction around, but that might make it all the better.

This centuries-old tree tells an unusual tale of vegetation and fertility in the desert.

This bridge was constructed from the rubble of the infamous Bastille.