This expansive bridge in the Canadian wilderness was originally just built for friends.

This series of rope-style bridges brings visitors into a jungle layer that is usually reserved for birds and monkeys.

At nearly 1,000 feet long, this astonishing glass suspension bridge is one of the longest in the world.

The latest in a series of long glass bridges suspended at terrifying heights.

The world's longest outdoor escalator takes visitors to the top of China's largest dam and is also shaped like a dragon.

This terrifying glass bridge on the side of a mountain cracks as you step on it.

A backdoor to Machu Picchu that only the most foolhardy infiltrator would attempt to breach.

Crossing this suspension bridge feels like walking through the sky, a fitting tribute to the head of the Apollo program.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

Watch the newest land on the planet form before your eyes.

This Yellowstone geyser may not shoot as high as the nearby Old Faithful, but it erupts for considerably longer.

These ruins of a pre-Columbian cliff village are among the most beautiful and well preserved in New Mexico.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

Massive mounds of golden sand look like a desert landscape randomly plopped in an Arctic forest.

Largest cave system in Africa.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

The largest earthwork effigy in the world.

An ancient iron pillar in Delhi that seems to be rustproof.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

Europe’s oldest natural human mummy.

The nearly 200-year-old folly has a secret spiral staircase hidden in one of its pillars.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

An exquisite tunnel of cascading flowers.