This was once the center of the Birdman cult, and is now a World Heritage Site.

Take shelter from Hawai'i's tropical heat under the massive canopy of largest Banyan tree on the island.

Site of James Cook's historic observations of the 1769 transit of Venus.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

Ancient cliffs resembling a kilt on Scotland's second largest island emit an entrancing sound.

This blowhole is supposedly caused by a trapped monster.

A once-glowing grotto at the bottom of Waikapalae Wet Cave.

The only arched bridge made of stone on the entire Mississippi River.

Secret hideaway for an alternative beach experience.

The fully functional, submerged Vanuatu Post Office is definitely one of a kind.

It's just another skyscraper, but it's shaped like '90s cell phone.

The king of U.S. high points towers over every other peak on the continent.

A hugely vast Irish landscape of barren rock that stretches for miles.

A former poultry store that looks like a giant duck and is one of the "seven wonders" of Long Island.

A 100-year-old purveyor of curiosities, curios, and kitsch featuring mummies, shrunken heads, and a Fiji Mermaid.

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

San Francisco's oldest surviving monument and meeting place for 1906 survivors.

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

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

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

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

Once the largest windmill outside of Holland, with enormous 114 foot sails.

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

This towering totem holds the title for the tallest in the world but only according to some.