The "stairway to heaven" lookout tower was built to resist weather, arson, and the laws of physics.

A rare example of World War I trenches from the British front.

A magical and peaceful ruined Cistercian abbey in what is now southern Belgium.

A lush indoor jungle fills this bustling Madrid transportation hub.

Eat like pre-Columbian Native Americans in this New Mexico restaurant within the Indian Pueblo Cultural Center.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

This amazing pedestrian suspension bridge in the Swiss Alps would give Indiana Jones nightmares.

An Australian lake whose pink hue defies scientific explanation.

A graveyard of old and rare planes that once were the glory of Persian aviation.

The colorful soil of Iran’s "Rainbow Island" attracts artists and nature lovers.

This lighthouse was crafted as penitence for the theft of wine bound for a monastery.

This massive steel pyramid can be entered by a set of jagged steps that let visitors stand in its heart.

At high tide this strange footbridge appears to have no purpose whatsoever.

One of the world's largest pyramids stands within El Mirador, the "lost city of the Maya."

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

You can only access this hermitage by crawling under a ledge suspended above an overhang.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

The world-record holder for the longest bridge stretching continuously over water.

A hidden tunnel leads to an abandoned slate quarry that's now a secret swimming spot guarded by cliffs.

This massive subterranean fissure is known as the "underground Grand Canyon."

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

The biblical sculpture honors those who lost their lives, homes and communities to the Chernobyl disaster.

At the right time of day, sunlight floods through the roof of this cave and illuminates the small pavilion hidden within.

A swing to dangle you off the very edge.