A Hawaiian stairway to heaven—that you can't climb.

Hidden behind a YMCA stands the remains of a ceremonial site that dates back hundreds of years, whose ground is still considered sacred to many Hawaiians.

Climbing this abandoned railway leads to breathtaking vistas of O‘ahu.

A unique set of caves that spits waves back out into the ocean.

Doris Duke's lasting collection of Islamic Art, hidden in a Hawaiian paradise.

This ancient Hawaiian henge may have been an early star chart.

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

Submerged lava formations create incredible waterworks.

This former luxury resort in Kaua'i is now an abandoned relic.

A prehistoric landscape hidden in the cliffs of Maha'ulepu.

A mysterious Neolithic tomb is perched along the edge of a modern golf course.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

This tiny train shuttles passengers to one of Northern Ireland's most spectacular sights.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

Amazing vistas await visitors to this stretch of coastline.

It is said a heartbroken man visited the gap every day to stare blankly out at the sea.

This mysterious Bronze Age standing stone has become a place where couples profess their love.

A peace symbol in Northern Ireland is among the world's largest hedge mazes.

A corkscrew-shaped barn in Ireland.

Achill's most recently abandoned village dates back to to the Age of Enlightenment.

These three lighthouses played a fundamental role in the maritime life of Eastham.

The largest glacial erratic boulder on Cape Cod.